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San Francisco, California 





JULY, 1931 


The Society of Motion Picture Engineers 

Its Aims and Accomplishments 

The Society was founded in 1916, its purpose as expressed in its 
constitution being "advancement in the theory and practice of mo- 
tion picture engineering and the allied arts and sciences, the standardi- 
zation of the mechanisms and practices employed therein, and the 
maintenance of a high professional standing among its members." 

The Society is composed of the best technical experts in the 
various research laboratories and other engineering branches of the 
industry in the country, as well as executives in the manufacturing 
and producing ends of the business. The commercial interests also 
are represented by associate membership in the Society. 

The Society holds two conventions a year, one in the spring and one 
in the fall, the meetings being generally of four days' duration each, 
and being held at various places. At these meetings papers are pre- 
sented and discussed on all phases of the industry, theoretical, tech- 
nical, and practical. Demonstrations of new equipment and methods 
are often given. A wide range of subjects is covered, and many of the 
authors are the highest authorities in their distinctive lines. 

Papers presented at conventions, together with discussions, 
contributed articles, translations and reprints, abstracts and abridge- 
ments, and other material of interest to the motion picture engineer 
are published in the Journal of the Society. 

The publications of the Society constitute the most complete ex- 
isting technical library Cor the motion picture industry. 




Volume XVII JULY, 1931 Number 1 



Color H. B. FRANKLIN 3 

The Multicolor Process RUSSELL M. OTIS 

The Multicolor Laboratory BRUCE BURNS 1 1 

The Latin- American Audience Viewpoint on American Films. . 


Improvements in Motion Picture Laboratory Apparatus 


Career of L. A. A. Le Prince E. KILBURN SCOTT 46 

Progress in the Motion Picture Industry: Report of the 
Progress Committee 

Committee Activities 


Patent Abstracts 

Officers 14G 


Contributors to This Issue 

Society Announcements 

I -( 
Report of the Treasurer. . . 





Associate Editors 




Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members, $12.00 per annum; to members, $9.00 per annum, 
included in their annual membership dues; single copies, $1.50. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930. at the Post Office at Easton, 
I 'a. under the Act of March :j, 1879. 



Summary. Brief comments are made upon the difficulty which motion picture 
directors and technicians experienced when color was first introduced into motion 
pictures. The importance of color in motion pictures and the progress that has been 
recently made in color processes are pointed out. Emphasis is laid upon the neces- 
sity for steady experimentation in color values and the use of good taste in the adapta- 
tion of color. 

Color as shown in motion picture production was virtually thrown 
upon an unprepared public. The introduction of color in motion 
pictures has suffered to a great extent through the fact that motion 
picture producers and their technicians were not prepared to give it 
experienced handling. In the early part of the last production sea- 
son, color was often introduced on the slightest pretext in many pro- 
ductions; producers did not have an opportunity to study the 
requirements nor perfect either the lighting or the apparatus to insure 
the best results. Consequently the color that was introduced so 
abruptly lacked the appeal that it could have had to motion picture 

That there is a place for color in motion pictures is a foregone 
conclusion. In this age, when color has so 'much appeal, the motion 
picture cannot be expected to be immune. The appeal for color is 
fundamental. Our every-day life is constantly surrounded by color. 
It is up to the producers, however, to make a careful study of the 
uses to which it is best adapted. When motion pictures can capture 
the blending hues of the spectrum so that they dissolve into the 
scene, so to speak and not dominate the picture as has been the case 
in some instances in the past then color will enhance the pictorial 
as well as the dramatic values in motion pictures. 

Much progress has been recently made in the introduction of per- 
fected processes. A real competitive situation is now developing 

* Presented in the Symposium on Color the Spring, 1931. Meeting at Holly- 
wood, Calif. 

** Hughes Franklin Theaters, Los Angeles, Calif. 


which should result in the production of better methods and lower 
cost. In the past the cost of color has been prohibitive and pro- 
ducers have been reluctant to adopt it generally. Now that color 
can be introduced at virtually little more cost than black-and-white, 
a greater interest may be expected. It is fair to assume that the 
prices will adjust themselves to lower levels as color is more widely 
used. In an effort to encourage its further use, the manufacturers 
of raw stock have reduced its cost according to the quantity used. 
Important plants are equipped to handle great footage and maintain 
high quality, propositions which have been difficult in the older 

Intelligent study and experimentation on color values is necessary 
if producers are to derive the greatest value from this medium. 
In the past, producers have been tempted to crowd scenes with 
blatant colors in an effort to emphasize a wide range of color. Some 
of the rooms shown in colored pictures would unnerve most people 
if used in actual life. It is to be expected that the producer would 
use the same good taste in motion picture scenes that he would use 
in an actual home. 

Lighting has been perfected to such an extent that it is unnecessary 
to handicap the use of color as it has been in the past, and with the 
new developments in photographic emulsions, a greater value may 
be placed on color as a medium. If the screen is truly to reflect life, 
it must eventually include color. 


MR. SCHLANGER: In the motion picture theater, color is employed to create 
a mood in the patron. It is my feeling that color in the film should be used for 
the same purpose to create a mood for the particular action on the screen rather 
than to show detail of color of the objects depicted. It is a delicate question 
as to what color will arouse the proper mood in the person viewing the film. 

Color will be tremendously important in the future for the reason that theaters 
will become simpler in design and will not rely upon colored decorations on the 
walls, ceilings, domes, etc., for creating the mood, as is at present done. The 
color on the screen might be utilized to take the place of colored decorations, the 
color being chosen so as to arouse the particular mood desired, and its reflection 
onto the simple decorations of the theater would provide the color projection 
which has before been suggested for the interior walls of a theater. 


Summary. A brief analysis is given of the way in which colors are reproduced 
using a two-color negative separation method. The Multicolor process, working on 
this principle, is briefly described. Details are given concerning the film used, 
camera requirements, exposure, development, printing, and coloring. 

The Multicolor process for making colored motion pictures belongs 
to the class of subtract! ve processes employing two-color separation. 
This means that in photographing, the light received by the camera is 
separated into two parts the blue and the red components. Each of 
these components acts on a separate negative emulsion. Positives 
are printed from these negatives and are colored, the one printed 
through the red-sensitive negative being colored blue and the other 
one red. These two colored positives are superimposed in projection 
so that the light which has passed through one positive is absorbed 
(or subtracted from) in passing through the other. 

Let us briefly consider how the various colors are reproduced. As- 
sume that a gray object illuminated by white light will reflect toward 
the camera such amounts of red and blue light as will produce equal 
densities on the two negatives. The positives will then have equal 
silver densities and, if the color values are properly chosen, the result- 
ing red and blue when superimposed will absorb equal amounts of 
the two complementary components of the projector light, resulting in 
only a decreased intensity, i. e., gray, on the screen. 

If the object to be photographed is not gray, but contains more 
blue than red, the red-sensitive negative will be less exposed than the 
other. The density of the positive printed from this red-sen- 
sitive negative will be greater than the density of the posit ivc 
printed through the blue-sensitive negative. Since the positive 
printed through the red-sensitive negative is colored blue it is obvious 
that when superimposed the two positives will transmit more blue than 

* Presented in the Symposium on Color at the Spring, 1931, Meeting at Holly- 
wood, Calif. 

** Hughes Development Co., Los Angeles, Calif. 


[J. S. M. P. E. 

red light and the screen image will lean toward the blue. If the object 
to be photographed reflects more red than blue, the same analysis 
will show how the red tones are obtained. 

It is not always appreciated that a two-color negative separation 
can result in many more than two colors on the screen. Most objects 
do not reflect a sharply defined spectral band but reflect to the camera 
light which affects both negatives to some degree. Hence a multitude 
of colors can be reproduced by making all possible combinations of 
red and blue densities. Thus many shades of blue, green, orange, 
red, and all the grays from white to black are obtained on the screen. 

What has been said thus far applies to all two-color subtractive 
processes, but the methods by which these results are obtained in 



FIG. 1. Spectrograms of Dupack through No. 
86 Wratten filter as used in daylight shots. Ex- 
posed in Hilger Wedge Spectrograph filtered to 

practice vary greatly. The process used by Multicolor will now be 

The separation of the two spectral regions in photographing is 
effected by the so-called bi-pack method. A special film with an 
orthochromatic emulsion and a standard panchromatic film are 
placed emulsion to emulsion, with the orthochromatic emulsion nearer 
the lens, and are run through the camera together. Blue or green 
light will expose the orthochromatic emulsion, but orange or red will 
not expose it due to the fact that this emulsion is not sensitive to 
orange or red. On top of the orthochromatic emulsion, on the side 
nearer the panchromatic film, is a layer of gelatin bearing a dye which 


passes only yellow, orange, and red light. By this means, the pan- 
chromatic emulsion, which is sensitive to all light, is permitted to 
record the yellow and red portions of the picture. Spectrograms 
showing the regions of the spectrum recorded on the two negatives 
are shown in Fig. 1. 

The camera used in photographing Multicolor pictures may be 
any camera employed for black-and-white work provided that a 
Multicolor double magazine for carrying the two negatives be used 
and that some special machine work be done to permit the camera to 
accommodate the two films and secure good contact between them. 
On the Mitchell camera a new pressure plate with four rollers is in- 
stalled to insure good contact between the films and a shim is placed 
in front of the ground glass to make the ground glass plane coincide 
with the plane of emulsions when two films are used. This camera 
can then be used at any time for taking black-and-white pictures by 
simply removing the shim in front of the ground glass. On the Bell 
& Ho well camera the pins on the back pressure plate are increased 
to eleven in number to insure contact, and 0.006 inch is removed from 
the aperture plate to make the emulsions come in the same plane as 
when previously only one film was used. In photographing, a No. 
86 Wratten filter is used for daylight shots but is not used when the set 
is illuminated by incandescent lamps. 

The prime requirement for good color balance over a wide range 
of exposure is that the gamma of the two negatives be the same and 
that the toe and shoulder of the H & D curve for one negative come at 
substantially the same points along the exposure axis as the toe and 
shoulder of the curve for the other negative. If the gamma of the 
two negatives is not the same it is possible to get a gray of only one 
density on the screen. If the H & D curves for the two negatives 
are displaced from one another so that the positions of the toes or 
shoulders of the curves do not coincide along the exposure axis, the 
efficient exposure range is narrowed to that between the toe of one 
curve and the shoulder of the other. In this process two negatives 
can be developed in the same time and in the same solution, and the 
success attained in meeting these requirements is demonstrated by 
Fig. 2. 

Rather than try to correct in the laboratory for improper exposure of 
the negatives, the illumination on the set is measured with a photome- 
ter. If the proper exposure is obtained it is possible to develop 
the negatives alike, print them with the same light, and develop the 



[J. S. M. P. E 

positive to a prescribed gamma, making the laboratory process nearly 
automatic. Generally, however, the printing lights are determined 
in the case of each scene by colored cinex strips. The determination 
of correct printing lights is one of the most critical operations in the 
laboratory process because it determines the relative density of the 
positive images, which in turn, fixes the color balance. A picture 
can be anything from an icy blue to a warm red, depending upon the 
choice of printing lights, and it is therefore essential that the man mak- 
ing the choice be equipped with facilities which enable him, when 
viewing cinex strips, to see the same thing that will afterward appear 
on the screen. 





/.<5 O 0.4 O.8 



FIG. 2. H. & D. curves of Dupack exposed through Wratten filter 
No. 86 in E. K. Co. sensitometer filtered to daylight, and developed at 
multicolor by machine. 

In printing, the two negatives go through the printer together, 
with a positive film between them. The positive film carries an emul- 
sion on each side of the film support so that each positive emulsion 
is in contact with its negative emulsion. The two positive images are 
printed simultaneously by light coming from each side through one 
negative. The positive emulsions are blue-sensitive and carry a yel- 
low dye to prevent light from one side exposing both emulsions. With 
the highest light used in printing, there is no exposure of the emulsion 
on the opposite side. The yellow dye washes out in the development 

July, 1931] 



The main problem in printing is one of obtaining good registration, 
which can be obtained by using adequate mechanical devices. The 
shrinkage of the films, and worse yet, unequal shrinkage, is om m 
the greatest difficulties. Unequal shrinkage has been considerably 
reduced by employing negatives which are made at the same time on 
base from the same batch. 

The positive is developed by machine to a prescribed gamma which 
has been determined by the condition that the contrast of gra\ 
the picture shall be the same as that of the grays in the subject photo- 

/2 /4 


FIG. 3. Per cent transmission of blue positive sound track vs. negative 


graphed. After fixing and drying, the film is then placed in the color- 
ing machine. 

The first operation of this machine is to apply a blue iron tone to 
one side of the film. Neglecting the washes, the film is then immersed 
in red toning solution which tones the image on the other side, leaving 
the blue image unaffected. This red uranium tone serves also as a 
mordant for a dye which next follows and which adds brilliance to 
the red image. The film is then passed through hypo after which it 
it is washed, dried, and varnished. This varnish greatly increases the 
life of the print, which is now ready for the projector. 

The problem of the colored sound track deserves mention. There 


is only one sound negative, so sound is printed on only one side of 
the positive, resulting in a colored track. A blue track has been 
found far superior to a red one. In variable density recording the 
blue track differs from the black-and-white track in the increased 
contrast of the blue over the black track before toning. Moreover, 
the relation between the response of a photoelectric cell to the trans- 
mission of the blue track and of the black before it is toned is not 
linear. The situation is further complicated by the recent introduc- 
tion of the caesium photoelectric cell which gives a result different 
from that of the potassium photoelectric cell when used to reproduce 
a colored sound track. 

The potassium cell is sensitive only to blue light, whereas the cae- 
sium cell responds also to red light. The effect with a black-and- 
white sound track is simply that the caesium cell reproduces with 
greater volume than the potassium cell. But when used with a 
colored track, the relation between the blue density and the black 
density is entirely different for the two cells, resulting in not only a 
difference in volume but generally a difference in quality as well. 

A study of the sensitometry of the blue track and recording tests 
made with it, however, have demonstrated that excellent results can 
be obtained with both types of cell if the sound negative is correctly 
exposed and if the remainder of the processing is properly done. It 
is particularly fortunate that the normal development of sound nega- 
tive to a gamma of about 0.5 is still found to be the most suitable 
when the sound positive is toned blue. 

The essential property of a good sound record is that there exists a 
linear relation between the transmission of the positive as viewed by 
a photoelectric cell and the exposure of the negative. Fig. 3 shows 
this relation for the Multicolor blue track as seen by both caesium 
and potassium photoelectric cells. 



Summary. This paper sets forth the manner in which the lay-out of the Multi- 
color Laboratory was made to provide efficient handling of all processing media, as 
well as film itself. A chart shows the flow of film through the various stages of handling 
and processing. Emphasis is laid upon the major precautions taken to protect all film, 
and particularly negatives, against damage of any sort at any point in the plant. 

Whenever a new laboratory for the processing of motion picture film 
is erected, the engineers of the industry naturally are interested in both 
the general layout and the particular features of design of building 
and equipment. In this paper will be briefly given a general picture 
of the new Multicolor Laboratory, placing some emphasis upon the 
features of design which are adapted to the special characteristics of the 
process, and the precautions which have been taken to insure safety 
to the product at all stages, particularly with regard to negatives. 

Fig. 1 shows a floor plan of the building, on which appear all film 
handling departments with the exception of the daily review room. 
In addition to these and the rooms containing equipment incidental 
to processing, such as boiler room, compressor room, refrigeration 
room, air conditioning room, etc., the first floor houses the general 
offices, the superintendent's office, the camera department, one pro- 
jection room, the electrical shop, a transformer room, a garage, and 
a room for general purposes, designated as the tank, repair, and stor- 
age room. 

No plan of the second floor is shown; it has approximately one- 
third the area of the ground floor, and in addition to the daily review 
room it includes four suites of executive offices, the research depart- 
ment, a theater, telephone room, etc. 

The heart of any film laboratory is its processing room, and the 
rooms for further treatment of film must be efficiently grouped around 
this unit. Since practically all other departments of the plant have 

* Presented in the Symposium on Color the Spring, 1931, Meeting, at Holly- 
wood, Calif. 

** Hughes Development Co., Ltd., Los Angeles, Calif. 

1 1> BRUCE BURNS [J. S. M. p. E. 

to handle film before it goes to the processing room or after it leaves 
the room, the disposition of these other departments should be such as 
to provide the nearest approach to continuous flow of the film through 
the plant. 

Similarly, since the chemical room must supply processing chemi- 
cals to the machines and receive chemicals from them, and the air 
conditioning equipment must furnish air for drying film in the ma- 
chines, both of these departments must be placed nearby. The power 
plant in which will be located the boilers to supply steam for heating 
the air during conditioning should be close to the air conditioning 
equipment. The compressor room, in which are located compressors 
for refrigeration and film squeegees, must be located properly both 
with regard to the processing room and the air conditioning equipment. 

Since it is evident that the size and shape of the processing room 
depends to a considerable degree upon the characteristics of the ma- 
chines employed, the first step in the lay-out of the plant is the selection 
of the proper processing equipment. When this has been determined, 
for the given capacity, the dimensions of the processing room are 
virtually fixed and the other departments of the plant may be ar- 
ranged around this room. 

The processing machines are of the continuous, multiple-strand, 
horizontal run type. Each machine is approximately 180 feet long 
in the wet end, and carries the same length of dry box to insure ample 
drying capacity under all conditions at a minimum temperature. The 
ten processing machines lie side by side in pairs with the dry boxes dis- 
posed on a mezzanine deck overhead. These machines occupy a 
processing room 44 feet wide and 225 feet long. 

At the east end of the processing room are placed the five air condi- 
tioning units, each with a capacity of 12,000 cubic feet of air per min- 
ute at a wet bulb temperature of 75F. maximum, which is ample for 
drying. The boilers for supplying steam to the air heaters are located 
south of the air conditioning equipment; the compressors and brine 
tank for supplying refrigerated water to the dehumidifiers are im- 
mediately west of the boiler room. 

The chemical room with floors or mezzanines on three levels is a 
narrow alley extending along the entire south side of the processing 
room; it contains the mixing tanks, circulating pumps, circulating 
tanks, and sump tanks for all the machines. 

Film handling rooms for work on the film before and after passing 
through the processing room are placed along the north side and west 

July, 1931] 



14 BRUCE BURNS [J. S. M. P. E. 

end of the room. The air conditioning equipment for this group of 
rooms is placed in the basement at the southwest corner of the proc- 
essing room. 

The printing room is equipped with Bell & Howell printers for 
sound track, and with Hughes Development Company step printers 
for picture. The latter have been designed with the specific require- 
ments of the Multicolor process in mind. They print from both 
negatives simultaneously onto the positive stock, thus insuring per- 
fect contact, register, and light balance. Each printer normally oper- 
ates at a speed of 21 feet per minute, but, if desired, can be operated at 
either lower or higher speeds. All picture printers are equipped with 
automatic light changes, which make it possible for the operator to 
devote his entire attention to the work of the machine, and although 
the printing operation is carried out on both sides of the film at once, 
a special inspection window with a mirror permits the operator to 
observe the film at the printing aperture at all times. In case any 
doubt arises in the operator's mind regarding any phase of the ma- 
chine's operation, he can stop and start it again between frames with- 
out affecting the finished print. 

By following the path of a roll of exposed double Multicolor Rain- 
bow negative from its entrance in the receiving department through 
the various steps in negative processing, and then following the posi- 
tive until it arrives at the shipping room door, we can see how the plant 
lay-out adapts itself to straight line flow. Referring now to the floor 
plan, we see that from the receiving room door the pair of negatives 
goes to the breakdown room, A, where tests are cut off and spliced 
into rolls for the negative developer. These tests are passed through 
a chute to the negative room and loaded on the machine at B. They 
go eastward through the negative machine, turn up at the east end of 
the process room to the dry boxes, and return to the west end of the 
room, where they are unloaded at C. Light tests are read at D and 
the results communicated to the breakdown room, where negatives 
requiring the same time of development are spliced into rolls and sent 
through the chute to the negative machines. From the loading point, 
B, they follow a course similar to the tests, are unloaded at C, and 
sent through the dumb waiter to the daily room. At E, rolls from the 
same production are made up and are sent to the cinex machine, F, 
where cinex exposures are made, after which the negatives are re- 
turned to the daily room at G. 

Raw stock goes directly through the receiving room into the raw 


stock room, K, from which it is supplied as needed for printing. 
Stock which is used for cinex exposures goes to the cinex machine at 
F and thence through a chute from the printing room to the west 
end of the processing room and through the light lock to the loading 
end, L, of a positive machine. As in the negative developer, films in 
the positive developer are developed, fixed, and washed on their trip 
to the east end of the room and are dried on their return to the west 
end on the upper level. They are taken from the positive machines 
at M, sent through the dumb waiter to the loading end, N, of the color 
machines, and go east through the wet end of the color machines 
and are dried in returning westward to point 0. From this point 
cinex strips go to the light reading table, D. Selection of proper 
printing lights is made, and the strips are sent through the dumb 
waiter to the daily room. Here, at G, the negatives are notched for 
light changes and light change cards are made out. From this point 
negatives go to the sound printer, H, then to the picture printer, /, and 
in the case of dailies they return to the daily room for transfer to the 
vault; in the case of release prints they shuttle back and forth be- 
tween the printing room and the negative polishing room, J, accord- 
ing to polishing requirements. 

The daily and release prints go from the picture printer, 7, through 
to the positive and color machines following the same course pre- 
viously outlined for cinex strips. Before being removed from the 
color machine at 0, prints are varnished and dried. Daily prints 
return in the same manner as cinex strips to the daily room, projec- 
tion reels are made up and go through the dumb waiter, T, up to the 
projection booth of the daily review room on the second floor, which 
is conveniently located with respect to the research department and 
sales department offices. Release prints leaving the color machines at 
O drop through a dumb waiter to release assembly, P, from which they 
go through inspection booths, Q, to hand inspection, R, where standard 
leaders are spliced on; from this point they go through the packing 
department, S, to the shipping room. 

Reference was made at the beginning of this paper to the safety 
precautions wjiich were taken in the design of the building and equip- 
ment; a few paragraphs will point out the highlights. 

The processing machines are so constructed that every strand of 
film is instantly available to the operator at every stage of the process. 
This permits continuous inspection, and in case a situation requiring 
immediate attention arises the operator can act at once without having 

16 BRUCE BURNS [J. S. M. P. E. 

to shut down the machine or wait for a length of film to run through 
one or more steps of the treatment. 

Although each air conditioning unit has a normal capacity, nearly 
twice that necessary for drying its quota of film, all five air condition- 
ing units are cross connected, so that in case of insufficient per- 
formance or complete failure of one unit the others may be called 
upon to carry the load. 

To guard against the possibility of a power failure stopping the 
machines with film in them, two thirty-three thousand volt lines from 
different power systems have been brought into the building, and in 
the transformer vault change-over switches are provided to shift the 
entire load from one line to the other in case the power is shut off. In 
addition, on the negative developing machine, a hand drive is pro- 
vided so that in the very remote case, where both sources of power 
fail, the operator can withdraw from the developer through the stop 
bath into the hypo all film which may be actually in the course of 

To guard against the possibility of water spots, double squeegees 
are used in series, so constructed that they may be cleaned while 
the machine is operating. 

Air for the squeegees is supplied by two double acting compres- 
sors, each driven by a two-speed motor. Under normal operating 
conditions both compressors running at half speed will carry the full 
load with an ample margin of safety. In case of failure of one com- 
pressor, the other, running at full speed, takes the entire load until the 
unit which has failed can be repaired, or the quantity of film in process 
has been reduced to half capacity. 

Similarly, two boilers are provided for the air conditioning and dis- 
tilled water service, either one of which is ample to take care of full 
production requirements. 

Three ammonia compressors are used for refrigeration in the air 
conditioning units. Under normal atmospheric conditions, one of 
these machines alone will carry the total load. All compressors and 
fans are driven by multiple V-belt drives, so that failure of one or more 
belts will not necessitate shutting down any unit. 

In the circulation of chemicals, excess pump capacity has been pro- 
vided. Where one pump will normally carry the load, another pump 
of equal capacity is always in reserve. Where two pumps are re- 
quired, an additional pump is provided to relieve either one. Also, 
large circulating tanks with a gravity flow to the processing machines 


have sufficient reserve capacity to make it possible to run film out of 
the machines in case of complete failure of all pumps. 

Two wells in the basement at opposite ends of the building, each 
with a capacity equal to normal wash water requirements, provide 
wash water of uniform and known chemical characteristics and tem- 
perature in winter and summer, but, in addition, a main from the city's 
water supply having sufficient capacity for the entire plant comes 
into operation automatically as needed. 

The building is constructed of flat slab reenforced concrete through- 
out and probably merits as nearly as modern construction can make 
it possible the appellation "absolutely fireproof." Automatic sprink- 
lers of the fusible link type have been installed in every room in the 
plant. In addition to this, extremely sensitive thermostats instantly 
responsive to slight but rapid changes of temperature, have been in- 
stalled where considerable quantities of film are to be stored or 
handled. As further evidence of the extreme precautions which have 
been taken to guard against fire, automatic sprinkler heads have been 
installed under cutting tables and in other places where appreciable 
quantities of loose film may easily accumulate. 

Reenforced concrete film vaults with specially constructed steel 
shelves are provided for storage of customers' negatives, and each 
vault has been made small so as to reduce to a reasonable minimum 
the amount of film concentrated at any one place. 

All film, whether negative, raw stock, or developed or colored posi- 
tive, is handled in specially constructed air-tight and light-tight, heavy 
gauge steel cans at every stage of its travel through the plant, except 
when it is being actually handled on one of the machines. 

Various minor precautions too numerous to mention have been 
taken to eliminate as nearly as possible all fire hazards; the success of 
this program is reflected in the fact that the Multicolor Laboratory 
carries the lowest fire insurance rate of any film laboratory in the 
United States. 



Summary. English language pictures accompanied by adequate Spanish titles 
still find favor in the chief markets of Latin America. Latin- American audiences 
want box-office personalities and through Spanish editions of our fan magazines 
nearly all our stars have built up a strong following. In consequence, pictures pre- 
senting them are more popular than Spanish versions in which the players are 

This does not mean that no Spanish language pictures should be presented. Great 
care should be taken in their preparation, however, and original subjects should be 
used of a type which have special appeal. Castilian Spanish, the language of the 
stage, should be used, unless the setting is in a Latin- American country where the 
actors would use the pronunciation and idioms peculiar to that country. None of 
the foregoing applies to Brazil, where the language is Portuguese. Here Spanish 
speaking pictures are not acceptable. 

The tastes of the Latin-Americans run to films containing much display in clothes 
and furnishings. High society pictures and musicals are both popular. 

While Latin- American revenues from film showings are not nearly as high as 
those received from Europe, the market is nevertheless well worth consideration. 
Argentina, Brazil, and Mexico stand fourth, seventh, and eighth, respectively, 
in quantity of motion pictures imported from the United States. There are about 
900 theaters wired and the number is rapidly increasing. 

Last fall, at the New York meeting of the Society, the writers en- 
deavored to outline in some detail the position of the American sound 
film in Europe. In this paper we are turning to Latin America. By 
so doing, it is intended to strike a somewhat different keynote, in 
looking at American films from the viewpoint of the audiences in the 
major Latin-American countries and attempting to indicate the type 
of film they like, placing special emphasis on the obstacles which the 
use of dialog has raised in an essentially non- English speaking region. 
For after all, while the audience is "king" in Europe as well as anywhere 
else, the European film situation is dominated by competition and 
government restrictions against our films. In Latin America both 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Chief and Assistant Chief, respectively, Motion Picture Division, Bureau of 
Foreign and Domestic Commerce. 


of these are happily absent and therefore the road to the box-office 
is comparatively free from those disturbing factors which sc^compli- 
cate the European situation. 

The fact that the bulk of our motion picture revenue conies from 
Europe should not blind us to the importance of the Latin-American 
market. After all, during 1930, over 73,000,000 feet of film from 
the United States were exported to the countries south of the Rio 
Grande. Argentina took from us nearly 17,000,000 feet of finished 
motion pictures and is our fourth largest market in quantity of films 
imported, while Brazil and Mexico, taking 11,312,000 feet and 9,417,- 
000 feet, respectively, stand seventh and eighth. In addition, an 
aggregate total of over 5,000,000 feet of film was sent to Chile and 
Cuba, over 3,000,000 feet each to Colombia and Peru, and over 
2,000,000 feet each to Venezuela and Uruguay. It should be noted, 
furthermore, that these figures represent showings of American films 
in all these countries averaging well above 80 per cent of their entire 
screen time. 

Latin America is still relatively deficient in number of wired 
theaters. Latest figures supplied by the Department's field men show 
that as yet only about 900 out of 5300 theaters are equipped for talk- 
ing pictures. However, these comprise nearly all the large first-run 
theaters, which supply a much larger proportion of revenue than their 
number would indicate. Furthermore, theater wiring is proceeding 
at a rapid rate. 

With this general picture of the situation in mind, the next question 
that arises concerns the kind of pictures that Latin-American audi- 
ences want to see. A rule-of- thumb answer to this question is, of 
course, impossible. However, we will present here a few impressions 
which have originated from our highly efficient trade scouts on the spot. 

In Cuba to begin with a market close at hand it appears that 
the women set the standard in films as they do in our own United 
States. That is to say, the society picture with elaborate costumes 
and settings is the prime favorite, although films of college life and, 
to a smaller degree, musicals are also popular. Westerns do not seem 
to enjoy much favor except among a limited portion of lower class 

As far as language is concerned, there seems to be a division of inter- 
est. For instance, in the five first-run houses in Havana and in tin- 
two movie houses in the fashionable Vedado residence district, dialog 
films in English predominate, due to the fact that these theaters are 

20 C. J. NORTH AND N. D. GOLDEN [J. S. M. P. E. 

frequented by Americans, English speaking foreigners, and by Cubans 
who, through travel and education, are more or less familiar with 
English. However, it is worthy of note that when such films enter 
the second- and third-run houses they are good for runs of only two 
or three days, as compared with a run at least three times as long for 
Spanish dialog features. This is true even in cases where the film in 
English presents popular stars and actors. 

In general, there has been no unfavorable reaction to the employ- 
ment of actors of different nationalities speaking the Spanish lan- 
guage. Naturally, if the setting of the film lies in a given Latin- 
American country, such as Mexico or Argentina, it would be expected 
that the actors would use those peculiarities of idiom and pronuncia- 
tion peculiar to those countries. It would also be expected that the 
diction and grammar of an actor would be in keeping with his station 
and environment. The anomaly of a day laborer speaking high-class 
Spanish would be quite as absurd as its American counterpart. But 
aside from these obvious limitations the use of Castilian Spanish for 
the average dialog film would be understood and appreciated by the 
Cubans. It may be added that virtually the same situation exists 
in Porto Rico, both as to tastes and type of language in favor. 

Turning now to Mexico, we find an interesting and peculiar situa- 
tion. There has been, and still is, a press campaign of considerable 
magnitude to ban the showing of all films in Mexico not in the Spanish 
language, and this campaign has had its effect in an attempt to ex- 
clude English dialog films by official decree, which so far has not 
come to anything. And yet, English language films are well received, 
particularly in Mexico City, and have a smaller though fair popularity 
in the large interior towns. Even the uneducated and semi-literate 
movie-goers do not object to English dialog if the pantomime and ac- 
tion is sufficient to make the story clear. 

An interesting experiment conducted in Mexico City not long ago 
by one of the large American companies illustrates graphically the 
relative box-office appeal as between English and Spanish dialog 
pictures. This company showed the English version of one of its 
productions in one theater and the Spanish version in another theater 
of relative size and catering to the same general class of audience. At 
the end of a week the company in question received the cheerful 
news that each theater had done better than average business and 
that the theater showing the Spanish version had grossed just $20 
more than the other. 


There have been two obstacles to the popularity of Spanish dialog 
films in Mexico. First, the value of the star cannot be overestimated. 
Mexican movie-goers read Spanish editions of the fan publications. 
They know all the American stars and they go to see them play in 
English, as against a picture in Spanish where the actors are com- 
paratively unknown. Of course, where American stars can speak 
Spanish, their popularity is just that much increased, but even though 
they speak English, they will not lose popularity until such time as 
Spanish actors develop a real star of their own. It might be added 
that one of the most popular types of film in Mexico is the American 
comedy in which the star for purposes of humor speaks what is re- 
ferred to as "gringo" Spanish. 

Another reason why Spanish language films have not been more 
sucessful is that many of the Spanish actors employ dramatic ges- 
tures and declamation which the Mexicans do not like nearly as well 
as the more simple and natural style of acting used in English lan- 
guage productions. As for the type of Spanish employed there is no 
objection to Castilian, if in part, but again, as in Cuba, great care 
should be taken to have the actors talk according to type, class, and 

In South America itself, our first and second markets are Argentina 
and Brazil. These have 1360 and 1600 theaters, respectively, while 
the former has about 260 and the latter about 200 theaters wired. 

Argentina has proved one of the greatest sources of difficulty for 
producers of Spanish language films. The taste of the people is es- 
sentially for high society films of a spectacular nature and for musicals. 
Sophisticated themes also appeal. Furthermore, the Argentim> 
public has its own particular ideas of Spanish and hence even t he- 
classical Castilian, which proves satisfactory (in its proper setting) 
throughout most of Latin America, is not very popular here. In 
short, Spanish dialog films have had only limited first-run success, 
though the desire for Spanish is strong enough among the lower classes 
to bring small profits in second- and third-run showings. 

Another and more important reason for the unsuccessful showing 
of Spanish dialog pictures is the lack of personalities which mean as 
much to the Argentine fan as to fans anywhere. Only special talent 
in Spanish casts of a type not discernible as yet can overcome this 
obstacle. And so we find the English dialog films with superimposed 
titles in Spanish ruling the roost and apparently destined to dominate 
the 1931 winter season. This, by the way, is in the face of a certain 

C. J. NORTH AND N. D. GOLDEN [J. s. M. P. E. 

amount of official and press opposition to the use of anything but 
Spanish in films shown in Argentina. 

Brazil is the single large Latin-American country in which Spanish 
is not spoken. The language is Portuguese and, while it is closely 
allied to Spanish and the people in general can understand that lan- 
guage, Spanish films are not acceptable. It therefore becomes a 
matter of showing films in Portuguese or in English with superimposed 
titles. Obviously, it is not financially expedient to produce Portu- 
guese versions except in special cases and even here those box-office 
names so dear to the hearts of the Brazilian fan are conspicuous by 
their absence. All told, the past year has shown that American 
talkies with Portuguese titles superimposed adequately and under- 
standingly are working satisfactorily. Dubbed pictures are not suc- 
cessful excepting in the case where a caption is flashed on the screen 
together with a definite statement that the picture had been ' 'dubbed" 
in the interests of realism. This was done by one of the exchanges in 
the case of a well-known picture and the audience took the inaccuracies 
of lip movement in good part. 

The past year has also demonstrated that the films which have been 
big box-office attractions in Brazil are drama done on a large scale 
with elaborate effects and plenty of action. Musicals, excepting re- 
vues, have fair popularity and high society portrayals are always effec- 
tive. Comedies not purely slap-stick get good returns, but typically 
American themes, such as the gangster film, do not go very well. 

The types of sound film most popular in Chile are the drama and 
musical revues. English language pictures were originally received 
enthusiastically and were very successful, but a sudden reaction has 
taken place and it seems that public interest in English speaking 
productions is on the wane. t 

The change from the silent drama to sound reproductions was a 
revolution in showmanship and a novelty to Chileans. The novelty 
has since disappeared, and several productions in Spanish have been 
shown and enthusiastically received by the movie patrons of Chile; 
the transition in public taste is toward Spanish dialog films. 

An indication of the above enthusiasm is well illustrated by the 
receipts of three American pictures. Two of these pictures each 
brought in about 200,000 pesos. In contrast, the third American 
film, featuring a well-known American star capable of speaking 
Spanish, it is estimated will bring upward of 450,000 pesos to its 


This is not to say that English dialog films in Chile with superim- 
posed titles are entirely out. The great majority of the better edu- 
cated class understand English and, furthermore, English is widely 
taught in the schools, as being the recognized language of commerce. 
It does, however, indicate that pictures having stars who are capable 
of speaking a type of Spanish not offensive to Chileans will have an 
edge in this market over those English dialog films with superimposed 
Spanish titles. But, as between an average Spanish version and a 
quality English dialog film with Spanish titles superimposed, the 
latter is at all times preferred. 

An interesting letter has recently been received from our Commer- 
cial Attache in Colombia, which describes the situation in that coun- 
try. He writes, among other things, "I have observed the reaction 
to talkies in Spanish and in English with Spanish titles, and have 
come to the conclusion that the latter combination is more successful." 
Perhaps the outstanding reason for the preference is that the actors 
and actresses in the Spanish versions are not as finished and well 
known as English speaking artists. Let the American producers 
continue to feature the well-known stars, have the parts announced 
in good Spanish, or insert brief but complete translations with the 
picture, a few musical numbers in Spanish, and the public will be 
satisfied. The Colombians like plenty of action, whether love, drama, 
or wild west scenes, and good music. In short, motion pictures with 
action and good music are the types that are attracting the public to 
the theaters. 

Peru with its 13 wired theaters also shows a predilection for the 
musical picture and the society drama. The opinion of the local pub- 
lic is divided, according to the opinion of our Commercial Attache* in 
Lima, as to whether English or Spanish dialog is preferred and as to 
the type of pronunciation which should be used in the Spanish dialog. 
Those who speak and understand both languages prefer English be- 
cause they claim that the English speaking actors are better. Good 
Spanish artists are preferred by those who do not speak English be- 
cause of the Spanish dialog, but they claim that the majority of 
Spanish actors have not been trained to acquire motion picture tech- 
nic, and therefore, the American box-office names are preferred at 
present by the greater part of the public. The local public does not 
want the dialog cut out because it is in English (which has been done 
with bad results several times in the past) for the reason that, among 
other things, the younger generation in Peru likes to follow English 


dialog because it helps them to perfect their knowledge of the lan- 
guage. As to the pronunciation preferred in Spanish versions, pure 
ilian, when not too exaggerated, is acceptable. The public is 
accustomed to hearing Spanish actors on the legitimate stage, where 
Castilian is the accepted language. 

It would be of interest at this point to quote the conclusions of the 
various consuls of Latin America who met in San Francisco recently at 
the suggestion of Don Sebastian de Romero, Consul of Spain, in that 
city, relating to the Spanish language to be used in talking pictures: 

"The Spanish language represents a complete unity to all those countries 
speaking it, with the exception of a few small differences in dialects pertaining 
to the different regions. The Spanish language as spoken by the cultured 
people of Latin America is as pure and as grammatically correct as that spoken 
in Spain by the same class of people. 

"We consider it worthy for all countries speaking our language to accustom 
their pronunciation to that of the Spanish language as spoken in Spain. In view 
of the fact that the sound picture is one of the best means for obtaining this 
uniformity in language, it is to be hoped that the actors taking part in these 
talkies will have a correct and pure pronunciation. There are, of course, in 
some of the Latin-American countries, as well as in the different provinces of 
Spain, certain accents and colloquialisms which will not be admitted in the 
talkies unless the parts are characterizing individuals of those countries and 

From all that has been said we must draw the highly surprising 
conclusion that the American product with Spanish sub-titles is more 
popular in the majority of Latin-American countries than the Spanish 
versions which are at present being shown. This should be good news 
to the producers who, having been told to produce films in the lan- 
guage of the particular country (still true in Continental Europe, by 
the way), are spending large sums in putting out Spanish versions 
of their product. However, it is not intended to assume that Spanish 
versions are, or should be, dead. Well done films in Castilian Spanish 
(except where special circumstances decree otherwise) will gain greater 
popularity in direct proportion to the time and care that is put on 
them, and it is quite likely, as Spanish box-office names are built up, 
that they may outstrip the American. The moral of the whole story 
is that Latin Americans as do fans everywhere go to see personali- 
ties a fact which producers sometimes overlook. 


MR. CRABTREB: What is meant by superimposed titles? Does the action 
proceed in English and stop at a title interpreting what has gone before in Spanish, 
or docs the title tell what is going to come? 


MR. GOLDEN: The superimposed title is on the set itself while the actors 
perform. It is seen in a lower corner of the picture, and explains tin lip motions 
of the actors In Japan and China, and in certain portions of India and C: 
a separate screen is used, on which is projected sub-titles which explain the action 
shown on the main screen. 

MR. GRUBER : Many English films have been translated into many languages, 
including Japanese and Polish; the Paramount eastern laboratories have done 
considerable work of this 'kind. 

MR. HICKMAN: About three months ago, in South America, I vi 
or three Latin-American films. On one side of the street was a theater showing 
an English-speaking talkie having Spanish titles superimposed on the sub-titlr. 
i. e., on top of the film action. Across the street a Spanish movie was going on. 
The all-Spanish movie sound reproduction was extraordinarily good and there 
was not a seat vacant in the entire house, which had a seating capacity of about 
1500. The people gathered there half an hour before the show. On the otlu-r 
side of the street, where the superimposed picture was being shown, there 
not fifty people in the theater. 

MR. GOLDEN: This might be true under certain circumstances, but reports 
on the situation have convinced us that it applies only when the natives of the 
particular country have seen the native actors; eventually they want to see our 
American stars. 

MR. CRABTREE: Perhaps, Mr. Bohm, you can tell us something of the 
German situation. Is the German language used in all the films or is English 
used in some of them? 

MR. BOHM: Two years ago there was really no production of German sound 
films in Germany. Since then American films have been shown. The first one 
was the Jazz Singer, in which the procedure outlined by Mr. Golden was followed. 
After seeing one or two pictures of this kind the German audience quickly came to 
dislike the superimposed titles. They wanted to have German films and hear 
the German language, but, in addition, they were prepared to listen, as a curiosity, 
to foreign films in their own language. Superimposed titles have entirely disap- 
peared in Germany in the last year and a half. Now the production of German- 
speaking films is very great and amounts to 100 to 120 feature films per \ 

MR. CRABTREE: Is it not annoying to have the hieroglyphics blotting out 
some of the detail of the picture? 

MR. BOHM : It is very disturbing, because one does not know whether to watch 
the action or read the lines. Translations are only of little lu-lp, since tlu-y 
detract the attention from the action, and I do not think that this kind of assis- 
tance to the distribution of film in foreign countries will last. The use of suprr- 
imposed titles does not answer the problem of foreign film distribution; it nuTi-ly 
furnishes a means of presenting American stars to the foreigner and gives him 
the continuity of the story. 

MR. KING: In China an additional screen is placed near the main screen, 
about H/2 ft. high and 3 ft. wide, on which still slides are shown. Three years 
ago the Chinese titles were placed immediately below the English title. 

MR. GOLDEN: I might also add that in Japan men known as "benshi" are 
employed to explain the action of the picture, as it proceeds, to those who are 
not capable of grasping the continuity without the aid of titles. 



Summary. A number of miscellaneous improvements in laboratory apparatus 
are described, which have for their object the elimination of spots, scratches, and 
uncvcnness of density in processed motion picture film. Modifications in developing 
room equipment include a vacuum cleaner for removing sludge from developers, a 
cooling coil for adjusting developer temperature, a new type of rack guide for a 
developer tank, a compact rack light lock, a waterproof and corrosion-resisting 
portable darkroom lamp, and some auxiliaries for the prevention of spots and con- 
tamination on film. 

Improvements in printing room equipment include the addition of a flywheel to 
a continuous printer to eliminate unevenness in density due to variation in the 
motion of the film during exposure. Also, a light change has been equipped to 
control either of two lamps of different wattage giving in each case exposure values 
which have precisely equal relationships. 

Some changes have been made in rewinding equipment which include the addition 
of a weighted roller to make more firmly wound rolls and a large portable winding 
core. The design of a standard disk rewind has been changed to facilitate removal 
of the wound roll. 

A film storage cabinet has been designed for laboratory use which gives an increased 
degree of protection from fire and water, at the same time assisting in the convenient 
and orderly arrangement of the film. 

Although essentially similar methods are in vogue for handling 
motion picture film in different laboratories, a great variety of equip- 
ment is employed for the various operations involved. This is due 
not so much to obsolescence as to lack of coordination of effort in de- 
signing equipment. 

It is the purpose of this paper to illustrate and describe some mis- 
cellaneous improvements in various types of laboratory equipment. 
Although parts of this paper dealing with rack equipment may be of 
little interest to those who use developing machines, it is hoped that 
they will be of value to many of the smaller laboratories which will 
undoubtedly use the rack system of processing for some time to come. 

* Presented in the Symposium on Laboratory Practices the Spring, 1931, 
Meeting at Hollywood, Calif. Communication No. 206 from the Kodak Research 

** Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 




Developer Clarification. With normal use, developers accumulate 
solid material which is in a fine state of division and remains in sus- 
pension for a considerable period of time owing to the agitation which 
the liquid receives. In the case of the almost universally used de- 
velopers of the "borax" type which contain a large proportion of 
sodium sulfite, a dark-gray sludge consisting partly of silver accumu- 
lates in the solution. The presence of silver is accounted for by the 
reduction to metallic silver of the silver halide dissolved out of the 
film emulsion by the sulfite. 

As the quantity of this material in suspension increases, it deposits 
on the emulsion surface of film processed in the developer and remains 

FIG. 1. 

Vacuum cleaner for sedimented sludge including 
water pump, trap, and nozzle. 

after the operations of fixing and washing are completed. Unless the 
squeegeeing or scouring operation is most carefully done, an objec- 
tionable quantity of the muddy residue remains on the film in the 
form of streaks which are noticeable on projection. No method 
has been found for preventing the formation of the mud but it can 
be removed from the developer by common methods of clarification. 
It was found that in a 120 gallon tank, 4 feet deep, a large propor- 
tion of the solid material would settle out from the developer upon 
standing overnight. After standing for twelve hours the largest pro- 
portion of the material settles to within a distance of about 1 inch 
from the bottom of the tank. 


Fig. 1 shows diagrammatically a device with which the sludge 
was removed from the bottom of the tank without causing any general 
agitation in the liquid. It consists of a metal vacuum nozzle shaped 
to lie on the bottom of the tank and held by a Ys-inch pipe which 
serves both for the vacuum connection and as a handle. The end is 
connected by a soft rubber tube to a laboratory water pump. 
A glass trap is inserted in the rubber pipe line to protect the pump 
and to permit continuous inspection of the sludge so that the 
operator may advance the nozzle along the bottom of the tank at a 
suitable rate. The water pump is especially suited for this work be- 
cause it develops sufficient vacuum for the purpose while the liquid is 
being raised but does not pump so fast as to cause an excessive flow 
of liquid. It was found that by using an experimental tank with glass 
walls, a nozzle of the type illustrated could be inserted in the tank 
and drawn along the bottom without scattering the mud. With a 
120-gallon tank the settled mud could be removed without taking 
out more than one gallon of liquid. 

If the developer is moved continuously in a large circulating system 
it might be possible to remove the sludge by continuous nitration. 
Alternatively, the main supply of developer might be divided into 
two or more parts so that sedimentation may take place in one part 
while the other is in use. The solid residue taken from various sam- 
ples of developer showed, upon analysis, between 13 and 47 per cent 
silver so that it is of sufficient value to be included with other silver 

Temperature Control. In the rack and tank process of developing 
where a recirculating system is not used, the developer temperature 
is likely to be other than what is desired after standing overnight. 
The temperature-control system, which functions while the developer 
is in use, should be designed to prevent a change in temperature due 
to continuous heat exchange and is therefore not usually capable of 
making a large change in the whole body of liquid in a short time. 
When a quick change is necessary, it has been found convenient to 
insert temporarily in the developer a length of metal pipe through 
which hot or cold water is circulated. For convenience in handling 
the pipe it has been found desirable to support it on a developing rack 
as shown in Fig. 2. By using about 18 feet of lead tubing and passing 
in water at a temperature 10 to 30 degrees, higher or lower than that of 
the developer it is possible to change the temperature of 120 gallons 
of developer several degrees per minute. Thin tubing of a corrosion- 

July, 1931] 



resisting metal such as monel or high chromium-nickel steel will 
permit greater heat transfer but the lead is satisfactory and is very 
easily shaped. 

Rack Guides in Tanks. In order to permit proper manipulation 
of the rack in a developing tank 1 it is necessary to leave room for its 
lateral movement. The ordinary type of rack guide which permits 
practically no laterial movement is quite unsatisfactory. Fig. 3 shows 
a two-rack stone tank fitted with maple rack guides which, while 
permitting considerable lateral motion of the rack when fully undi-r 
the surface of the liquid, hold it in such a way when locked that no 
part of the film comes in contact with or dangerously near any part 
of the tank. 

FIG. 2. Cooling pipe mounted on developing rack. 

It will be noticed that the whole assembly of wood at each end of 
the tank is attached to the center guides which extend from top to 
bottom of the tank. They are kept in position at the bottom of tin- 
tank by means of a hole into which they fit and at the top by attach- 
ment to the wooden framing which surrounds the tank. Rotation 
is prevented by the flat side which they present to the end of the tank. 
A slot is cut in one guide to make room for the thermometer and in 
the other for clearance around the drain hole. Allowance is made for 
expansion of the wood both where the peg enters the bottom of 
the tank and at the ends of the cross-piece holding the lower outside 



[J. S. M. p. E. 

guides. Maple has been found more satisfactory for work of this 
kind than cypress, which is often used where it is to be in contact with 
water. No trouble is experienced from warping, probably because the 
wood is wet equally on all sides. Wooden dowel pins are used ex- 
clusively for joining the pieces which are to be in the liquid. 

When the rack is first lowered into the tank considerable freedom 
of motion is permitted, but when it is pushed down far enough to slip 
under the ledges which hold it in place it comes to the lower side guides 
which deflect it inward from the tank wall toward the center guide. 





i e 


FIG. 3. Stone developing tank with rack guides. 

At the top of the tank it is kept well away from the side of the tank 
by reason of the location of the locking ledge at the front which ex- 
tends only a short distance from the center guide. At the back of the 
tank the rack end is held under a ledge from which it is released when 
the rack is drawn toward the front end preparatory to lifting it out. 
The upright ends of the rack extend farther beyond the cross bar at 
the upper end of the rack than at the bottom so that the film is always 
well below the surface of the liquid when the ends of the uprights are 
held under the ledges. 

July, 1931] 



Rack Light Lock. Where space is limited the usual types of light 
lock for passing racks of wet film to the light room from a very dark 
room are not possible. Fig. 4 shows schematically a rack light lock 
which occupies only the same floor space as a single rack tank. The 
doors are stepped so as to provide complete light locking and are 
hinged on the side so that they can be opened and closed very quickly 
and require a minimum of space. When either door is closed it re- 
leases the two locks holding the other. A spring hinge opens the door 
as soon as it is released but the door is stopped by a safety catch when 

I / 

> \ 

FIG. 4. Light lock for developing racks. 

it is free of the lock at a point about 1 inch from the jamb. When 
a rack is to be passed the operator releases the catch, allowing the door 
to open wide. 

The inside of the light lock is fitted with a guide track for the rack at 
top and bottom. The lower guide is continued in the floor about one 
rack length outside the light lock, to assist in directing the rack prop- 
erly in the darkness. A safelight illuminates the interior of the light 
lock and the extension of the lower guide. 

Waterproof Hand Lamp For use in the developing room an ordi- 



[J. S. M. P. E. 

nary type of flashlight is too easily damaged by liquids to be depend- 
able. Either the switch fails, the dry cells are damaged, or the safe- 
light filters are injured within a short time after it becomes wet. 

A safe hand light has been designed which will not be damaged by 
continual immersion in water or developer. As shown in Fig. 5, the 
lamp consists of a monel metal tube closed at either end by caps fitted 
with soft rubber gaskets. The dry-cells, switch, and lamp are en- 
closed within this seal and the safelight glass is held against the gasket 
in one cap. The lamp is screwed into a reflector of the usual type and 
is electrically connected with the battery in the ordinary manner ex- 
cept that the switch is of the mercury type which closes the circuit 
when it occupies a certain position. The choice of a switch of this 


FIG. 5. Waterproof flashlight. 

type eliminates the need for lever or sliding parts extending to the 
outside of the tube. 

A switch of the type indicated, when mounted as shown in the figure, 
opens the electrical circuit when the lamp rests in a vertical position 
on the wide end or when allowed to come to rest on its side. The 
flange just back of the safelight is eccentric and is provided with a 
flat spot at the lowest position so that if it is laid down on its side it 
rolls to a point where the current is switched off. To obtain light, 
the lamp is turned in the hand until the circuit is closed. 

Glove Cleaning Equipment. Very serious trouble in the form of 
spots or streaks on the film can result from contamination by chemi- 
cals carried on the hands or gloves in the developing room. If no 
otlur provision is made it is necessary for the operator to attempt 

July, 1931] 



rinsing gloves in a film washing tank, usually with poor results and 
considerable hazard to the contents of that tank. The use of a faucet 
is slow. The equipment shown in Fig. 6 makes the rinsing operation 
easy, quick, and effective. 

Two lengths of metal tubing were drilled with Yie-mch holes and 
bent to the form shown in the figure, so that a glove held within the 
loop can be rinsed by streams from all sides at once. The washers are 
very convenient when mounted as shown with guards to confine the 
spray. Superstainless steel was used in the construction so that tin- 

FIG. 6. Spray washer for cleaning gloves. 

rinsing equipment could not of itself be a source of contamination as 
a result of corrosion. The water is controlled by a pedal valve so 
that the gloves are not polluted again in shutting off the water. 

If it becomes necessary for a developing room man to handle 
alternately racks carrying wet and dry film, the gloves must be dried 
effectively before he takes a dry rack otherwise the film is very likely 
to be spattered. Wiping with a towel is not satisfactory because 
even with great care, water often remains between the fingers in drops 
which are thrown off when the hand comes to a stop suddenly in grasp- 
ing the rack. 


This wiping can be done effectively by means of a compressed-air 
"brush" which consists of a straight length of metal pipe or tubing 
drilled with small holes somewhat similar to that described above for 
rinsing. With a supply of filtered compressed air at a pressure of 
10 pounds or more the gloves will be entirely free of water after about 
two passages in front of the blast of air from the small holes. The 
water is knocked off by the force of the air so that the action is very 
rapid. In this case the pipe should not be bent into a closed loop 
because water is likely to remain on the metalwork and be picked up 
by the dry glove as it is withdrawn. A pedal valve is most convenient 
for controlling the compressed air. 

Goggles. Between 20 and 30 minutes are required for practically 
complete adaptation of the eyes of a person entering a room lighted 
in a way that is safe for panchromatic film after being in daylight or 
a well lighted room. This adaptation is lost in a few moments if he 
returns to a brightly lighted room after which it is necessary to go 
through the long process of adaptation again. It is helpful to those 
in a laboratory who are required to pass to and from such darkrooms 
to use dark goggles while in the light room so that the eyes remain 
adapted to the darkened condition. The visual density of the gog- 
gles should be about 3.0, which is about the least that can be used 
without allowing serious change in adaptation level. A more dense 
glass reduces the visibility excessively in the light room. This figure 
is relative to the conditions encountered but can be understood to 
apply to good artificial illumination and a typical panchromatic dark- 
room where indirect lighting is used. Very cheap goggles of the kind 
supplied with "health" lamps can be obtained from the manufacturers 
of goggles. The glass referred to is designated by their number 10. 


Balance Wheel for Continuous Printer. In a continuous printer 
the negative and positive films must be drawn past the printing aper- 
ture at a constant speed so that irregularities will not be introduced 
into the picture or sound prints as a result of variations in the time 
of exposure. Irregularities of motion of the same magnitude may be 
tolerable in a step printer if their frequency of occurrence is very 
much greater than the time required for printing one frame and if they 
sum up to produce a substantially constant total time of exposure for 
every frame. In a continuous printer, if the motion of the film is 
retarded or accelerated momentarily, the part passing the printing 

July, 1931] 



aperture will receive more or less exposure than adjacent parts. 
These variations due to mechanical irregularities in the driving mecha- 
nism often occur several times while a single frame is passing the 
aperture and are frequently of such magnitude as to produce very 
objectionable cross lines in the print. 

This irregularity can be corrected by using a constant-speed motor 
and by protecting the sprocket shaft from 
influences which tend to produce momen- 
tary departures from continuous motion. 
The best device for the purpose is a fly- 
wheel used in combination with a vibra- 
tion-absorbing drive coupling 2 by means 
of which unevenness of motion in the 
drive train is minimized. 

In an installation of a flywheel in a con- 
tinuous printer the original shaft was re- 
placed by a longer one capable of carrying 
the flywheel, as shown in Fig. 7, and was 
supported by an outbearing installed for 
the purpose. The sprocket was attached 
by a rigid coupling at the end of this new 
shaft. Beyond the outbearing a single 
bearing was installed to carry a driving 
shaft. At one end this driving shaft is 
connected to the gate sprocket shaft by a 
vibration-absorbing coupling consisting of 
a short piece of rubber hose, and at the 
other end it carries a pulley. Power is 
transmitted to this pulley by a belt from 
the speed reduction at the motor. 

The feed and take-up sprockets in this 
printer are geared directly to the shaft of 
the gate sprocket. Unless the moment of 
rotation of the gate sprocket assembly 

could be made very great it was feared that unevenness in motion 
might result from the reaction of the drive gears of the other spnx 
A 30-pound flywheel, proportioned as shown in Fig. 7, was chosen. 

The printer was tested carefully by making a flash exposure on a 
strip of motion picture positive film while the lamp intensity was 
held constant. It was found that the flywheel had overcome UK- 

FIG . 7. Flywheel mounted 
on shaft of gate sprocket in a 
continuous printer. 


UIK venncss of motion of the film at the gate. This test also con- 
firmed the opinion that any tendency toward unevenness caused by 
the other sprocket drives was overcome by the large moment of the 

Light Change Rheostat for Lamps of Different Power. Light change 
units have been produced by means of which negatives requiring a 
large number of light changes can be made without resetting. 
Such devices, if portable, can be used with any printer when the na- 
ture of the work requires it. 

FIG. 8. Rewind with weighted roller for winding a firm 

In some laboratories different types of printer are used in which 
lamps of different power are required by the differences in time 
of exposure. It is desirable that the exposures given by the two types 
of printer be equal for corresponding light control steps so that the 
scene charts can be used interchangeably. Therefore the portable 
light change unit must be equipped with two rheostats, one for each 
type of lamp, and a means for switching from one to the other. 

A unit of this kind has been equipped to give 17 equal exposure 


steps with either a 60-watt, 120-volt lamp with S-l cage filament, or 
a 250-watt, 120-volt projection monoplane filament lamp. 

Two resistances were constructed by winding a wire of low tempera- 
ture coefficient of resistance on pipe clay cylinders. Brass clamps 
were slipped over the rheostat to permit tapping off the various steps 
of resistance required. Clay supports of the same size were used for 
the two rheostats but allowance was made in the choice of wire size 
and the closeness of winding to provide the necessary resistance and 
for the dissipation of heat. Lead-in wires were carried from the 
clamps to an 18-pole, double-throw switch, by means of which the 
several bus-bars in the selector panel could be connected to the sev- 
eral taps of the 60-watt or 250-watt rheostat, respectively. A sliding 
contact type of switch was used although an enclosed mercury switch, 
while rather expensive, would be preferable in most cases because it 
requires less attention. 

The 60-watt lamp was used in a printer equipped with a light con- 
trol designed to give a range of intensity of 1.0 to 100.0 in equal 
logarithmic steps. The necessary lamp current values had been 
calculated by means of the lamp data and formulas given 3 by 
C. Tuttle, and are shown in Table I. The printer in which the 250- 
watt lamp was to be used was equipped with a manually controlled 

diaphragm light change. 

Step Relationship for 60-Watt Lamp, S-l Cage Filament 

Number (Relative) Log C C (Calc.) 

1 0.0 T.4471 . 0.280 

2 0.1176 1-4594 0.288 

3 0.2352 1.4718 0.296 

4 0.3528 I. 4841 0.305 

5 0.4704 1.4965 0.314 

6 0.5880 1-5100 0.324 

7 0.7056 1.5212 0.332 

8 0.8232 1.5345 0.342 

9 0.9408 1.5458 0.351 

10 1.0584 1.5582 

11 1.1760 1-5706 

12 1.2936 1.5833 

13 .4112 1.5954 0.394 

14 .5288 1.6066 0.404 

15 .6464 1.6190 

16 .7640 1-6323 

17 8816 1.64-17 0.441 

18 20 1.6571 0.454 


Since the relative illumination efficiencies of the optical systems in 
the two printers were not known, it was necessary to determine by 
photographic tests a set of conditions under which exactly equal ex- 
posures were given, and then from the data, to calculate the lamp 
current values at which the other exposures would be obtained. 

It was found that when the 250-watt lamp was operated at 101.9 
volts in the printer where it was to be used an exposure was given 
which was equal to that given in the other printer by the 60-watt 
lamp operated at 106 volts. The expression for the current-voltage 
relation, as given by Tuttle, is 

V = aC b 

where C is the current in amperes, V is the voltage, and a and b are 
constants. The current flowing, when the voltage drop across the 250- 
watt lamp was 101.9 volts, was calculated and found to be 2.132 am- 
peres. The formula given by Tuttle relating the lamp current with 
the intensity is as follows, M, K, a, and b being constants: 

log / = (& + 1) log C + log a - log K 
or transposed: 

log C = '" w * l b l +*~ (2) 

By substituting the values of M, K, a and b } for the 250-watt lamp 
this equation reduces to 

log C = 0.807 log / + 0.0204 (2a) 

The actual intensity is not known, but instead, that given when the 
lamp current is 2.132 amperes is considered as having the relative 
value of 100. It was therefore considered desirable to modify the 
constant term in equation (2a) to agree with this value. Accordingly 
the logarithm of 100, or 2.0, and the logarithm of the current, 2.132 
amperes, or 0.3287, were substituted in the equation in the form 

log C = 0.807 log/ + k 
0.3287 = 0.807 X 2.0 + k 

which gave a value for 

k = -1.285 

Now, it was necessary to calculate, by means of the equation con- 
taining this new constant and having the form 

log C = 0.807 log / - 1.285, (26) 

July, 1931] 



seventeen other values of lamp current corresponding to 17 steps in 
lamp intensity, each differing from the next by an equal logarithmic 
difference. Since the total change in 17 steps is as 100 to 1.0 of which 
ratio the logarithm is 2.0, then each log intensity step has a value of 



= 0.1176 

The values of log / and log C for the 250-watt lamp are shown in 
Table II. 

Step Relationship for 250- Watt Lamp 













1 . 1760 



C (Calc.) 


As an alternative to these calculations a graphical method could 
have been used, plotting log C against log /. In his paper Tuttle 
gives a number of corresponding values for intensity and lamp current. 

By using an ammeter in series with the lamp and light change unit 
the resistance taps were adjusted to give the required lamp current at 
each light change step with the line voltage constant. Each rheo- 
stat was adjusted in this manner while connected to its proper lamp. 

In another instance it became necessary to use a lamp for which 
data were not available. The photographic characteristics of the 
lamp were determined as follows: A uniform density step tablet on 
motion picture film was chosen for the measurements. For the most 
dependable results the tablet should have density steps of approxi- 
mately 0.15 from zero to 3.0 and should be developed in a developer 



[J. S. M. P. E. 

which produces a silver image having no color selectivity of light ab- 
sorption. If the developer contains no other developing agent than 
don this condition can be obtained. With a tablet of this character 
it is not necessary to make any correction of the visual density. 

A number of prints are made from the tablet on motion picture 
positive film with the lamp to be measured in the printer. In each 
successive print the lamp current or voltage is varied in a definite 
manner so as to cover the range of intensity found necessary in pre- 
vious trials. The number of exposures made should be about equal 

FIG. 9. Disk rewind close-up showing stripper fingers 
for facilitating removal of wound roll. 

to the number of steps which will be used, say, 15 or 20. These prints 
from the step tablet are developed together, great care being taken to 
assure uniformity, for a time sufficient to produce a gamma of at least 
1.0. The densities are read and plotted, on a single sheet of paper, 
against the densities of the tablet from which they were printed. A 
number of characteristic curves are produced which have the same 
slope but which are separated from each other along the tablet density 
axis. These displacements are taken as a measure of the log exposure 
differences for different lamp currents. By reading the position of the 

July, 1931] 



curves along the scale of tablet densities in the reversed direction, 
relative values for log intensity of exposure corresponding to the val- 
ues for lamp current used in the 
tests are obtained. If these values 
for relative log intensity are plotted 
against the logarithm of the lamp 
current a straight line is obtained 
from which lamp current values for 
any lamp intensity step relation- 
ship can be chosen. Also, if de- 
sired, the lamp constants can be 
determined for use in the formula. 
It is well, before using the avail- 
able data, to check the electrical 
characteristics of a representative 
group of the lamps at hand. This 
check will usually be sufficient to 
detect changes made from time to 

time by the manufacturers. If the electrical characteristics change 
appreciably, it is advisable to make new photometric measurements as 
described above. 


Film Roll Winder. A large proportion of the surface injury to film 
is a result of cinching which occurs during winding. It is especially 

FIG. 10. Transportable and col- 
lapsible winding core of 2-inch di- 

FIG. 11. Parts for assembly of portable winding core. 

desirable, therefore, to wind negative film in such a way as to make 
firm rolls which will not be cinched on subsequent rewinding. A good 



[J. S. M. P. E. 

method of securing tightly wound rolls is to allow an idle roller to 
ride on top of the winding roll. In this way the film is pressed against 
the roll by a force applied perpendicularly to the direction in which 
the film travels so that there is no danger of cinching. Fig. 8 shows 
a winder of this type with a guide roller at the lower left. Both rollers 
are undercut so that they bear on the film only near the edges. 

Stripper Fingers on Disk Rewind. Trouble is experienced fre- 
quently when it is attempted to eject a roll of film from the core of a 

FIG. 12. 

Motor-driven rewind with speed- 
control pedal. 

disk rewind by means of the disk. This is more commonly found 
with rewinds which have become worn so that there is excess clearance 
between the disk and core. When the disk is moved, one convolution 
of film slips into the space around the core and the disk becomes jam- 
med. This difficulty is overcome in a type of core (Fig. 9) which is 
slotted to admit four stripper fingers attached to the face of the disk. 
These fingers prevent the film from slipping between the disk and 
core. This trouble is avoided also if the film is wound on a portable 
core such as that described in the section below. 

July, 19311 



Large Winding Core. Cinching is usually worse near the ends of 
rolls which have been wound on very small cores. In Fig. 10 is shown 
a portable aluminum core 2 inches in diameter by means of which the 
treatment of the film during winding is improved. The core is 
slipped over the special core described above or an ordinary 1-inch 
hub modified by increasing the width of the slot to admit the key 


13. Close-up view of drawer of valuable film storage 

which is built into the core. The core is collapsed for removal when 
the roll is to be stored or shipped out of the laboratory by moving the 
small lever seen in the top surface in Fig. 10. A novel means is 
used for preventing the film from slipping on the core, which consists 
of a thin piece of soft rubber cemented in a slot in the core. When 
the film is wound tightly around the core it presses against the rub- 
ber, which protrudes about VM inch. When the core is collapsed for 



[J. S. M. P. E. 

removal from the film, the rubber is no longer in tight contact and the 
core can be slipped out easily without the film adhering. The core 
is composed of two pieces of aluminum, three pieces of steel, and two 
screws. The parts are illustrated in Fig. 11. In this figure can be 
seen the eccentric pin by which the expansion of the core is positively 
e fleeted. 

Motor Driven Rewind. In winding operations where it is necessary 

for the operator to have both hands 
free for the work, an electrically 
driven rewind is helpful. This applies 
particularly to cleaning, where it is 
preferable not to have to stop fre- 
quently to apply cleaning solvent to 
the cloth. Fig. 12 shows a rewind 
driven by a variable-speed motor. 
The controller, operated by a pedal, 
gives a choice of speeds which covers 
the range required by the varying 
diameter of the roll. It would be pos- 
sible to make the film travel at a 
constant speed by allowing a roller 
riding on the winding roll to vary the 
speed of the motor continuously. 


The storage cabinet described in 
a previous communication 4 was de- 
signed for permanent storage and does 
not lend itself readily to the needs of 
the cutting room, where it is neces- 
sary to put away for short periods of 
time pieces of valuable film of various 
lengths. A slightly modified type of 
cabinet has been designed, which per- 
mits more convenient inspection of the contents of each drawer. As 
shown in Fig. 13, the drawer is somewhat larger than in the type in- 
tended for permanent storage and has a hinged cover which can be 
raised after the drawer is drawn partly out of the cabinet. This 
cover, which must be closed completely before the drawer can be 
pushed back in place, has a rim which enters into a close fitting well 

FIG. 14. Overnight storage cabi- 
net for valuable film. 


so as to make a tight closure. Near the back of the drawer but inside 
of the fire flap is a coarse wire screen to prevent the film cans from be- 
ing pushed out into the flue when other cans are put in near the front. 
In Fig. 14 the cabinet is shown as it stands in a vault. 

Acknowledgment is due to various members of the Research 
Laboratory and Development Department who gave counsel and 
suggestions in the design of the equipment described. 


1 CRABTREE, J. I., AND IVES, C. E.: "Rack Marks and Airbell Markings," 
Trans. Soc. Mot. Pict. Eng., No. 24 (1926), p. 95. 

CRABTREE, J. I.: "Development of Motion Picture Film by the Reel and 
Tank Systems," Trans. Soc. Mot. Pict. Eng., No. 16 (1923), p. 163. 

2 ELMER, L. A., AND BLATTNER, D. G.: "Machine for Cutting Master Disk 
Records," Trans. Soc. Mot. Pict. Eng., No. 37 (1929), p. 227 

3 TUTTLE, C.: "Illumination in Printing," Trans. Soc. Mot. Pict. Eng., No. 
36 (1928), p. 1040. 

4 CRABTREE, J. I., AND IVES, C. E.: "The Storage of Valuable Motion Picture 
Film," J. Soc. MOT. PICT. ENG., 15 (March, 1933), p. 239. 


Summary. I n November, 1886, Le Prince, an inventor and scientist living in 
New York, N. Y., applied for a U. S. patent covering a photographic camera which 
would expose successively a number of images of the same object or objects in motion 
and reproduce the same in the order of taking. Although the patent granted him 
on January 10, 1888 (U. S. Pat. 376,247), described a camera having sixteen lenses, 
it is shown that the original application specified "one or more lenses." His British 
patent No. 423, accepted Nov. 16, 1888, provided for both a camera and projector 
with one lens as well as multiple lenses. Most of Le Prince's important work was 
done in England and France from 1887 to 1890 with a single-lens camera, at 
least two of which were built and used. Descriptions are included of these cameras 
as well as a multiple lens camera. Evidence is introduced concerning the design 
of the cameras, such as the use of the Maltese cross intermittent movement, and of 
the building of and demonstrations with a projector. 

Louis Aim Augustin Le Prince was born 89 years ago (Fig. 1). 
His father was a major of artillery in the French Army, an officer of 
the Legion of Honor, and was an intimate friend of Daguerre, the 
famous pioneer of photography, who gave his son some early lessons 
in the art. 

Le Prince was educated in colleges at Bourges and Paris and did 
post-graduate work in chemistry at Leipsic University, which was 
very useful for his future career. He was a born artist, and, after 
some training in Paris, took up oil painting and pastel portraits; he 
also specialized in the painting and firing of art pottery. 

In 1866, he met a friend, John R. Whitley, who afterward became 
famous as the builder and organizer of the first exhibitions at Earl's 
Court, and also as the builder of Le Touquet in France. He invited 
him to Leeds, and Le Prince decided to remain and join the firm of 
Whitley Partners, brass founders, of Hunslet, as designer, afterward 
taking charge of the valve department. 

In 1869 he married Miss Whitley, who had been trained as an artist 
under Carrier Belleuse, the director of the Government pottery of 

* Reprinted with permission from the Photographic Journal, May, 1931. 
Recommended for publication by the Historical Committee. 

'* Consulting Engineer, London, England. 


Sevres. His father-in-law, Joseph Whitley, was a remarkably clever 
inventor, who introduced, among other things, the method of spinning 
large cylinders and pipes from molten metal. 

During the Franco-Prussian War, as an officer of volunteers, Le 
Prince went through the siege of Paris. After returning to Leeds, he 
and Mrs. Le Prince started a school of applied art in Park Square, 
the first of its kind in Leeds. 

Le Prince carried out color photography on metal and pottery and 
fixed the colors in a special kiln. He executed commissions for Roy- 
alty, and his portraits of Queen Victoria and W. E. Gladstone were 

FIG. 1. Louis Aime Augustin Le Prince. 

placed in the foundation stone of Cleopatra's Needle, along with other 
records of the time. 

In 1875 the series of photographs taken by Eadweard Muybridge 
at Palo Alto, Calif., were published, and Le Prince was attracted to 
the idea of producing a series of photographs, in other words, "motion 
pictures" with one camera. Muybridge employed about two dozen 
separate cameras, and his mode of taking the photographs in sequence 
was limited and not suitable for reproducing the illusion of motion. 

48 E. KILBURN SCOTT [J. S. M. P. E. 

Le Prince had been working at this for some time, when, in 1881, 
his brother-in-law, who had become interested in the Lincrusta- Wal- 
ton process, invited him to go to New York to assist in introducing 
that process. He went, and, on the patent rights being sold to an 
American company, had to find something else to do. 

Mrs. Le Prince and the family had joined him meanwhile and de- 
ciding to stay on, he became manager of a group of French artists who 
produced large circular panoramas. One in New York showed the 
battle between the Monitor and the Merrimac. Others were in Wash- 
ington and Chicago. 

Jean Le Roy, of New York, who was employed by Joseph T. 
Thwaites, the English photographer, from 1872 to 1879 and from 1882 
to 1888, has written as follows: 

"I met and became acquainted with Le Prince about the spring of 1884, 
when he came to my employer's studio and photograph gallery at No. 1 Cham- 
bers Street, New York City. I recollect an order was for a number of lantern 
slides of military scenes, that he explained were to be made to scale so that he 
would be able to project them without any varying sizes or proportions. It 
was to help him to make outline drawings on canvas to be used in a panorama of 
war. This was built at 59th St. and Lexington Ave., in later years converted 
into the 71st Regt. Armory, and now the site of the Plaza Theater. The last 
time I saw Le Prince was in 1887." 

At this time, Mrs. Le Prince was teaching art at the Institute for 
the Deaf on Washington Heights, New York, N. Y. Her husband 
became friendly with the principal, Isaac Lewis Peet, and was per- 
mitted to use the tools and facilities of the institution's well-equipped 
workshop. Joseph Banks, the mechanic, who is still living in New 
York, assisted Le Prince in the constructional work and recalls the 
early attempts to make motion picture machines. 

When a child of 14, Miss M. Le Prince went one evening to the insti- 
tute. Seeing a light shining under the door, she entered and saw her 
father and Joseph Banks operating a machine which threw dim out- 
lines of figures on the whitewashed wall. Thus the first projected 
motion pictures of Le Prince the earliest in America were 
screened in the Institute for the Deaf. 

In 1886 Le Prince drew up a specification giving full details and 
working drawings, and applied for an American patent in November 
of that year. Three clauses of the application read as follows: 

(1) The successive production by means of a photographic camera of a 
number of images of the same object or objects in motion and reproducing the 
same in the order of taking by means of a "projector" or "deliverer," thereby 

July, 1931] CAREER OF L. A. A. LE PRINCE 49 

producing on the eye of the spectator a similar impression to that which would 
have been produced by the original object or objects in motion. 

(2) In an apparatus for producing "animated" pictures the continuous 
alternate operation of the film and its corresponding shutter or series of shutters. 

(4) As a means of producing "animated" pictures on a photographic receiver 
provided with one or more lenses and one or more shutters, in combination with 
one or more intermittently operated film drums. 

Being a good mechanical draughtsman, he made his own drawings 
for the specification and showed the most difficult proposition, 
namely, a machine with 16 lenses. It is important, however, to note 
that his specification, as first filed, covered any number of lenses from 
one upward. 

On January 10, 1888, the U. S. Patent Office in Washington granted 
his patent, No. 376,247, entitled "Method of, and Apparatus for, Pro- 
ducing Animated Pictures." They, however, cut out claims for 
machines with one lens and with two lenses, giving as the reason that 
Dumont's British patent No. 1457 of 1861 was an interference. 

Le Prince was in England at the time and did not know that this 
had been done until it was too late for effectual protest. His patent 
attorneys, Munn and Co., very foolishly permitted the patent to be 
issued without challenge, and so it stands in the American records. 

Many consider the attitude of the Patent Office to have been wrong 
because the Dumont patent was in no sense a motion picture device. 
It was for photographs on glass plates, arranged to form the facets of 
a prismatic drum, the object being to enable one to choose the best 
single photograph out of several successive ones. Dumont's object 
was not to show continuous movement by projecting pictures on a 
screen, which was the purpose of Le Prince. 

In a statement of his father's claims, made in 1898, Adolphe Le 
Prince wrote quite fairly that: 

"He was the first investigator to grasp the value and necessity of an unlimited 
amount of pliable film, moving from a supply drum, on which it was wound 
as many times as desired; not just a circumference length as Dumont had in 
mind. In the Le Prince apparatus the part of the film acted on was, at that 
instant, between the upper and lower drums, and therefore flat, being addit 
aided by a clamping pad and tension device; this enables the Le Prince apparatus 
to take large pictures, and yet have perfect focus; both these points are primary 
necessities for good projection of 'Animated Pictures' on a screen. 

"Marey, in 1885-1886, working independently on somewhat the same lines 
as my father, added greatly to the understanding of 'Animal Locomotion' and 
its more specific allies, but h had not used an endless pliable film, nor a me* 
for definitely cutting off one phase from the next. His work has been given U 
credit it deserves." 



[J. S. M. P. E. 

Miss M. Le Prince, who saw pictures which her father took between 
1885 and 1887, and which he projected on a wall of the Institute for 
the Deaf, has stated that some were taken with a single-lens camera- 
projector, and others with a four-lens camera. The pictures were 
about I 1 /* inches in diameter. 

It is important to note that his British patent No. 423, applied for 
on the date of the issuance of his American patent, January 10, 1888, 
and accepted November 16, 1888, provided for a "receiver" (camera) 
and "deliverer" (projector) with one lens as well as multiple lenses. 
Otherwise it differs in no other essential particular from his United 
States patent. 

Front view. Rear view. 

FIG. 2. Le Prince 16-lens camera. 
(Reproduced by courtesy of the Science Museum, London.) 

Later, similar patents were issued by France, Italy, Austria, and 
Belgium, without the Dumont patent or any other being cited against 

Obviously, if a machine could be designed and made to work with 
16 lenses, it was easier to make it with 8 or 4, and easiest of all with 
only one. We do know that practically all Le Prince's most impor- 
tant work was done with one-lens machines. The camera which Le 
Prince made in Leeds in 1887-1888 had only one lens, as Mr. Frederic 
Mason (who helped to make it) and myself have repeatedly stated. 
(See appendix.) This is fully demonstrated by the actual machine 
now in the Science Museum, London. 

July, 1931] CAREER OF L. A. A. LE PRINCE 51 

Le Prince returned to England in May, 1887, and then stayed with 
his mother in Paris. While there he gave attention to the taking out 
of his French and other continental patents. To facilitate this and 
demonstrate "proof of working," as it is called, he made a camera- 
projector with 16 lenses (Fig. 2). 

FIG. 3. Le Prince single-lens camera; 1888 (front). 
(Reproduced by courtesy of the Science Museum, 
London, England.) 

The particular model brought from New York by Miss Le Prince 
is now in the Science Museum. It is constructed to take two bands of 
film of sensitized gelatin, mounted side by side on rollers in a chamber 
attached to the back of the camera. Of the sixteen lenses, eight 



[J. S. M. P. E. 

facing one film were released in rapid succession, after which the re- 
maining eight lenses were discharged while the first film was being 
moved on ready for another set of pictures. Each film was clamped 
during exposure by a frame operated by a cam. 

The lenses were operated by an ingenious system of double shutters 

FIG. 4. Le Prince single-lens camera; 1888 (interior). 
(Reproduced by courtesy of the Science Museum, Lon- 
don, England.) 

worked by a series of electromagnets connected to a battery and a 
circular electric switch. On rotating the handle of the switch, the 
shutters operated in regular and rapid succession. Two additional 
lenses were provided as view finders, one for each film, in con- 

July, 1931] CAREER OF L. A. A. LE PRINCE 53 

junction with a bellows placed at the back of the apparatus; focusing 
could be done while the machine was working. 

Several sets of motion pictures were taken, including one of the 
mechanic who assisted Le Prince to make the machine. They were 
projected on a screen in the Paris Opera House on March 30, 1890. 
The Secretary of the National Opera made a statement, of which the 
following is a translation: 

"I, the undersigned, Ferdinand Mobisson, Secretary of the National Opera, 
Paris, residing at 38 Rue de Mauberge, certify by this present to have been 
charged with the study (or examination) by means of the apparatus brought 
before me, of the system of projection of animated pictures, for which Mons. 
Le Prince, Louis Aime Augustin, of New York, United States, has taken 
out in France patent rights dated the llth of January, 1888, having the number 
188,089, for 'Method and Apparatus for the projection of Animated Pictures, 
in view of the adaptation to Operatic Scenes,' and to have made a complete 
study of this system. 

"In faith of which, I have delivered the present certificate to serve whom it 
may concern. 

"Paris, March 30th, 1890. 

"(Signed) F. MOBISSON." 

Before going to Paris he had been to see William Mason and Son, 
woodworkers, of 150 Woodhouse Lane, Leeds, and secured the ser- 
vices of Frederic Mason to make parts of cameras, etc. On returning 
to Leeds, he rented a workshop at 160 Woodhouse Lane, and employed 
as assistant a clever mechanic, James W. Longley, who had done work 
for him at Rhodes Bros., Engineers, of Leeds. Some of the metal work 
was also carried out at Whitley Partners, his father-in-law being much 
interested in the invention. J. W. Longley was also an inventor, 
and made the first machines to deliver tickets automatically with 
coin-freeing mechanism. They were used at the Leamington athletic 
ground, Leeds. 

By the summer of 1888, he had completed two cameras, each with 
a single lens, and (with the one also shown to The Royal Photographic 
Society and now in Science Museum) had photographed a series 
of pictures at the rate of 12 per second in the garden of his father-in- 
law at Roundhay. The following is a description of the camera 
(Fig. 3 and Fig. 4): 

The film, 2 3 /s inches wide, is wound from one to the other of a pair 
of ebonite spools about six inches in diameter, one above the other. 
The top one is revolved intermittently by a cam bearing a number of 
teeth which engages with projections on the hub of the spool, 
film is thus drawn up through the "gate" behind the lens in a series of 


[J. S. M. p. E. 

iVrks. At each exposure, it is held fast by a flat brass plate also oper- 
ated by a cam. The plate moves back slightly when the film is 
being pulled through, to prevent scratching. Many years later, this 
last device was claimed by firms as being original with them. 

Light is cut off from the film during movement by a circular slotted 
brass shutter which revolves behind the lens in the same way as in 
modern machines. The shutter is a robust affair, and the opening 
in it is adjustable. Focusing is accomplished by means of a rack and 
pinion movement operated by a lever at the side, the front, bearing 
the lenses, and shutter being moved back- 
ward and forward. There is, of course, a 
finder lens attached above. 

To assist in promoting smooth, even mo- 
tion the spindle of the lower spool carries a 
heavy brass flywheel. The intermittent 
drive on the top spool was unvaried, what- 
ever the amount of film the latter carried. 
Le Prince's assistant, James Longley, wrote: 
"As the drum gets larger, it takes more material 
to go round. All we had to do was simply rewind 
the band of pictures off the drums of the camera 
machine on to the drums of the delivering machine 
and start the delivering machine with the same 
end of band of pictures. They would travel at the 
same rate in both the machines." 

A series of pictures (Fig. 5) was taken by 
Le Prince in 1888 in the garden of his father- 
in-law, Joseph Whitley, at the residence 
now called Oakwood Grange, Roundhay, and 
occupied by Sir Edwin Airey, and the win- 
dow shown in the photographs can still be 
seen. His son, Adolphe Le Prince, wrote 
the following on a print of these pictures: 

"Portion of a series taken early in October, 1888, by the second one-lens 
camera. Le Prince's mother-in-law in this picture died October 24, 1888. Le 

* This series was taken with a one-lens camera at rate of 10 to 12 images per 
second, in the garden of his father-in-law, Mr. Joseph Whitley, Roundhay, Hunslet, 
Leeds, England. Le Prince's son, Adolphe, and Mr. and Mrs. Whitley are shown 
in the picture, with a younger lady. The date is definitely determined because 
of the death a few days after of Mrs. Whitley. Le Prince cranked the camera and 
probably used gelatin or glass plates on the carrier in his camera, not having 
yet obtained celluloid film. 

FIG. 5. Two Frames 
of a series taken by Le 
Prince,|October, 1888.* 

July, 1931] CAREER OF L. A. A. LE PRINCE 55 

Prince's eldest son is also in the picture, as is his father-in-law. Taken from 
10 to 12 a second. There was no trial of speed contemplated here." 

The following statement was also made by him on prints of the 
series of pictures taken from a window of the premises of Hick Broth- 
ers, at the southeast corner of Leeds Bridge, which firm supplied Le 
Prince with tools and materials: 

"Portion of a series taken by Le Prince with his second one-lens camera in 
October, 1888. A view of the moving traffic on Leeds Bridge, England, taken 
at 20 pictures a second in poor light. His eldest son was with him when he took 
the picture." 

James W. Longley wrote about them in the following characteristic 

"Leeds Bridge where the tram horses were seen moving over it and all the 
other traffic as if you was on the bridge yourself. I could even see the smoke 
coming out of a man's pipe, who was lounging on the bridge. Mr. Augustin 
Le Prince was ready for exhibiting the above mentioned machine in public. 
We had got the machine perfect for delivering the pictures on the screen." 

For taking these pictures, Le Prince used sensitized paper film, and 
one of the exhibits at the Science Museum is a reel of this material. 
It is on record that Le Prince used gelatin stripping film when East- 
man introduced it. In any case he had no trouble in getting good 
photographs at 12 to 20 per second. The pictures of Leeds Bridge 
were on film 2 l /% inches square. 

To project the pictures on a screen was more difficult, for the reason 
that the film had to pass close to a lamp, and the heat made the 
material cockle or blister, and put the pictures out of focus. 

His great problem was to obtain a suitable supporting base for his 
emulsion and, as mentioned in the specification, he tried horn, mica, 
hard gelatin sheets, and collodion sheets; also, at one time he used 
glass positives, attached to bands moved by sprocket wheels. 

His patent specification refers to material carrying the film trans- 
parencies, reading: 

"Punched with holes fitting on the pins of the guide rollers; also sensitive 
film for the negatives may be an endless sheet of insoluble gelatin, coated with 
bromide emulsion or any convenient, ready made, quick-acting paper." 

His eldest 'son, Adolphe, who left a record of the experiments, 
stated that his father went to all the photographic supply houses in 
England, France, and the United States to obtain suitable material. 

He obtained a supply of sensitized celluloid in sheets about a foot 
square, which he cut into positives and printed from the roll negative 
films. These he mounted on flexible, robust carrying bands. 



[J. S. M. p. E. 

Finally, the coining of long sensitized celluloid strip or film did 
away with the bands. 

Evidence of his skill in making apparatus is well shown by the two 
large reels of celluloid, one of which is in the Museum (Fig. 6). 
They are of strips of celluloid 3 inches wide and about 12 inches long, 
cut from sheets and joined by pieces of silver. Two strips of silver 
along the edges are bent to form regular projections to keep the layers 

These particular reels were used for developing his exposed films, 
which were rolled up in the spool of celluloid, the whole being then 
immersed in the developer. The silver projections allowed space 
between each coil for the solution to reach the film. The celluloid 

FIG. 6. Spools for developing film; Le Prince, 1888. 
(Reproduced by courtesy of the Science Museum, London, 

is pierced with holes to allow the developer free access to the film. 
The strip has a matte surface on one side. This idea was patented 
years later by another inventor, but if the authorities had known of 
Le Prince's arrangement they would not have allowed the patent. 

Examination of the clever mechanism of the camera and the con- 
struction of the spools gives the impression that Le Prince had the 
ability to cope with all the problems necessary to make motion pic- 
tures a commercial success. Had he lived, he would have been a 
master figure in the industry. ' 

He had the usual characteristics of the true inventor, and was 
always making improvements. His projectors or "deliverers" went 
through many stages with the object of simplifying the mechanism. 

July, 1931] CAREER OF L. A. A. LE PRINCE 57 

In the winter of 1888-1889 he built a "deliverer," or projector, hav- 
ing three lenses and three belts, which is thus described by his son: 

"In this machine the belts, at slight tension, were moved by teeth pulling in 
the eyelets of the three belts, and rapidly stopping and starting at equal intervals 
(depending on speed of rotation of main shaft) by means of three 'pintooth' 
wheels timed to correspond with the opening and closing of the time 1 
The opening and closing were governed by a slotted circular shutter, rapidly 
rotating on a shaft. A gear wheel on the end of this shaft conmcti -<1 with the 
feed gear, and completed the harmonious action of the feed shutter and stopping 
and starting device. This deliverer gave continuous illumination on the si 

"He also constructed in 1889 a one-lens deliverer, the picture belt being arranged 
in an endless spiral, the pictures appearing before the lens in rapid succession, and 
storing automatically as soon as projected and released." 

A sketch made by his assistant, Longley, with descriptive letters, 
shows that the three-lens "deliverer" used the Maltese cross to give 
intermittent picture shift (Fig. 7). He says: 

"g is the star wheel arrangement for allowing the band to work at the proper 
time. The wheel with the pins is for gearing into the band of pictures and should 
have two rows of pins, one on each side and we had brass eyelets fixed in the 
band similar to the eyelets of boots." 

Being an artist, Le Prince appreciated the importance of color, 
and the patent specification he wrote in 1886 says: 

"Once developed and toned the transparencies may pass through the hands 
of artists who will tint them in transparent colours, dyes, or lacquers as the subject 
may require." 

In 1889, Le Prince constructed a projector to work with one lens, 
and decided to use an electric arc light instead of oxy-hydrogen pre- 
viously employed. For this purpose, he came to his friend, Wilson 
Hartnell, an electrical engineer, of Leeds, by whom I was employed. 
I went to see about it and entering the workshop at 1(50 Woodhouse 
Lane, saw his assistant, Longley, whom I had known for some years. 
Noticing a large sheet at the end of the room, I asked if it was for a 
magic lantern, and his reply was, "Much better than that; the pic- 
tures actually move and represent life." 

In due course, the plant was installed, direct current being gem-r- 
ated by a Crompton dynamo driven by a semi-portable Robey boiler 
and engine in Mason's yard. That was at No. 150, and permission 
was obtained to carry the cables over intervening buildings to No. 160. 

A difficulty in recording the history of events is that those who were 
eye-witnesses die. However, I state positively that the projector and 
the camera worked with single lenses, and William Mason and Wilson 
Hartnell have told me about seeing Le Prince's pictures on the screen. 



[J. S. M. P. E. 

FIG. 7. Photostat of memorandum and sketch prepared by Longley, 
who assisted Le Prince in constructing his cameras. 

July, 1931] CAREER OF L. A. A. LE PRINCE 59 

The unveiling of a tablet on Le Prince's workshop (Dec. 12, 1930) 
has brought forward letters from people who would not otherwise 
have been traced. One from Walter Gee, chief engineer to the British 
Barnsley Co-operative Society, says: 

"I am very pleased to give my testimony about the pioneer work of the late 
Louis A. A. Le Prince and confirm what I know of particulars given in your 
pamphlet about the electric installation. 

"During the late eighties I was an electrician with Wilson Hartnell, 
M.I.Mech.E., Consulting Engineer, of Basinghall Street, Leeds, and worked 
on the installation for the supply of electricity to an arc lamp in Le Prince's 
workshop at 160 Woodhouse Lane, Leeds. 

"Mr. Le Prince worked his projector machine and showed moving pictures 
on a white sheet hung at the other end of the room. 

"At the time of the first switching on, there was one other person present 
beside Mr. Le Prince and myself, namely, James W. Longley, who was his 

"I know nothing of details of construction of the projector machine, but I 
was very pleased to see it work so well. I noticed how Mr. Le Prince opened 
his mind as he was working it, for he had been very quiet up to then. . . . 

"Regarding the time of the electrical installation, my recollection is that it 
was about the middle of 1889. In 1890, I came to Barnsley, to put in plants 
for the Barnsley British Co-operative Society, where I have been ever since 
and am chief engineer. 

"(Signed) WALTER GEE." 

J. T. Baron, chief electrical engineer of the Metropolitan Borough 
of St. Pancras, 57 Pratt Street, London, N.W.I, writes: 

"I well remember the occasion of Mr. Le Prince's experiments about 1889 in 
Woodhouse Lane, when, along with others of Mr. Wilson Hartnell's staff, I 
was sent to see about fixing up the equipment, consisting of a dynamo and electric 
arc projector, for what was known to us then as moving pictures. 

"I trust you will get further support for the interest you have taken in the 
recognition of Le Prince. 

"(Signed) J. T. BARON." 

Arthur Wood, engineer and machinist, of 331 Pietermaritz Street, 
Pietermaritzburg, Natal, wrote on the 25th of November, 1930: 

"In 1388, two years prior to my leaving Leeds for South Africa, I was with 
the firm of Whitley Partners, Railway Works, Leeds. The head of the firm in 
those days was Mr. Joseph Whitley, a very capable man, one who would spend 
thousands of pounds in experiments for his business, and greatly interested in 
anything unusual. 

"I can very well remember Le Prince's invention, as, while I was with Mr. 
Joseph Whitley, I personally made mechanical parts of the projector, such as 
the pedestal, gears, chains, etc. I was shown the film for which it was made, 

60 E. KILBURN SCOTT [J. S. M. P. E. 

and if my memory holds good this film was of a horse galloping, although I did 
not see it actually projected. 

"(Signed) ARTHUR WOOD." 

Certain people have said that Le Prince was not the pioneer he is 
claimed to be because he only made machines with multiple lenses. 
This mistaken idea has been helped by the description given in Hop- 
wood's book, Living Pictures, and on seeing what he had written, I 
told the author he was wrong. Unfortunately after Hopwood died, 
Mr. Bruce Foster, also of the Patent Office, repeated the error in a 
second edition. He has, however, written me the following letter: 

"I have been away for a few days and have been looking through the various 
documents you have sent me, more particularly in respect of the bearing of the 
information thereon in the relevant matter in Hop wood's Living Pictures for 
the second edition of which I must plead guilty. 

"There can be no question of fact that Le Prince's specification of 423/1888 
includes the proposition of a 'one-lens' camera and projector. The specification 
includes the following passage in addition to the claims cited on p. 7 of the 

'" 'When the receiver is provided with one lens only as it sometimes may be, it 
is so constructed that the sensitive film is intermittently operated at the rear 
of the said lens which is provided with a properly timed intermittently operated 
shutter, and correspondingly in the deliverer, when only one lens is provided, 
the band or ribbon of transparencies is automatically co-operated so as to bring 
the pictures intermittently and in the proper order of succession opposite the 
said lens.' 

"It is a matter for regret that this aspect of Le Prince's specification was not 
brought out clearly in the second edition of Hopwood's book. The reason 
probably was that the specification described in greater detail the multiple-lens 
construction. This fact cannot, however, be relied on to exclude a 'one-lens' 
construction according to the specification. 

"If, as it would appear from the information you have, the film referred to on 
p. 6 of the pamphlet shows Mrs. Whitley walking in the garden, and can be 
identified as taken with a 'one-lens' camera, then, as Mrs. Whitley died on the 
24th October, 1888, these facts alone would appear to date the 'one-lens' camera 
as made before that date. 

"I am sorry the storm of controversy should be so tied up with the detailed 
paragraphs in Hopwood's Living Pictures, and apart from my regret that the 
existing text does not give due weight to the 'one-lens' proposition in the speci- 
fication of 423/1888 if the story has to be rewritten it will have to be modified 
also in other particulars, in the light of new facts which were not put in my pos- 
session when the second edition was published. 

"(Signed) E. BRUCE FOSTER." 

Le Prince worked with collodion and gelatin for several years and, 
when living in New York, must have heard that Hyatt Bros., of 
Newark, were engaged on the problem. They made sheets of trans- 

July, 1931] CAREER OF L. A. A. LE PRINCE 01 

parent celluloid by veneering it from a large block. Afterward it 
was made by spraying on glass. 

John Carbutt sold sensitized celluloid sheets late in 1888, and 
showed this material and photographs made on it at the Franklin 
Institute, Philadelphia, in November of that year. 

Rev. Hannibal Goodwin, of Newark, N. J., was evidently in touch 
with Hyatt Bros., for in 1887 he knew enough about the possibilities 
of celluloid film to apply for an American patent in that year. Dr. 
Marey, of Paris, is said to have used sensitized film in the late eighties. 

There is very little doubt that long sensitized celluloid strip be- 
came available in 1889, and Le Prince had some reels of it in that 
year. Frederic Mason was employed to cut each reel into two to suit 
Le Prince's machines, as declared before a Commissioner. (See 

The 1889 patent of W. Friese-Greene and Mortimer Evans makes 
mention of "sensitive photographic film;" however, there is no special 
merit in mentioning a material which anyone could buy. If cellu- 
loid film had been on the market when Le Prince applied for his first 
patent 2 1 / 2 years before, i. e., in 1886, he would most certainly have 
mentioned it along with the other materials. 

Le Prince had trouble with his film cockling and getting on fire 
with the heat of the lamp, and the water screen he made is thus de- 
scribed by Longley: 

"It was made of two plates of glass and thick India-rubber put between and 
clamped with brass plates across, also two syphon tanks so that the water was 
continually changing." 

They fully recognized that in the use of sensitized celluloid film the 
last hurdle had been cleared. It was the production of satisfactory 
transparent, pliable, and robust films that finally brought motion 
pictures into commercial use in the middle nineties. In that work 
many inventors, engineers, and commercial men helped. 

In the spring of 1890, Le Prince decided to return to his family in 
New York, and ordered special boxes to be made to carry his appa- 
ratus. These boxes recently came back to Leeds as containers of the 
original apparatus, which was shown at the unveiling of the memorial. 

In preparation for showing her husband's apparatus and pictures, 
Mrs. Le Prince rented the Jumel Mansion in New York and had it 
redecorated. The home life of the family was ideal and she was a 
splendid helpmate. 

"Proof of working" of his first French patent was granted in June, 

62 E. KILBURN SCOTT [J. s. M. P. E. 

1890, and there is no doubt but that he then had business in that 
country. In August he went to France with his friends, Mr. and Mrs. 
Richard Wilson, and left them at Bourges to visit his brother, an 
architect and surveyor of Dijon. He was last seen entering the train 
for Paris at Dijon on September 16, 1890, and then he disappeared, 
together with his luggage. Intensive searches were made by French 
and English detectives, but not a single clue was ever discovered. 

Some time after his disappearance, Mr. Richard Wilson collected 
such things as he thought worthy of preservation. As a banker he 
did not know their technical and historical value, and thus films, etc., 
were lost that would now be considered valuable. Charles Pickard, 
commercial photographer of Leeds, has the tripod of the camera and 
Frederic Mason picked up a few photographs. 

It will be remembered that much the same thing happened in the 
case of Friese-Greene, practically all his apparatus being sold for 
"junk," only a few pieces of film being saved. In the case of Friese- 
Greene, no machines remain, but in the case of Le Prince there are 
two, fortunately, to testify to his ingenuity. 

When it became certain that her husband was lost, Mrs. Le Prince 
consulted with Mr. Choate, sometime American Ambassador to Great 
Britain, but all he could tell her was that she would have to wait until 
the death could be legally "presumed," which took seven years. In 
1898, the eldest son visited England and France and took back to 
New York the camera and other things, some of which are now de- 
posited in the Science Museum at South Kensington. 


1 SCOTT, E. KILBURN, "The Pioneer Work of Le Prince in Kinematography," 
Phot. J., 63 (Aug., 1923), pp. 373-8. 

1 CRAWFORD, MERRTTT: "Louis A. A. Le Prince," Cinema, 1 (Dec., 1930), 
pp. 28-31. 



In 1887 I was near the end of my apprenticeship with my father's and brother's 
firm, Wm. Mason & Son, joiners and contractors, of 150 Woodhouse Lane, Leeds, 
and one day there came to the works a Mr. Louis Augustin Aim6 Le Prince 
who previously had been with Whitley Partners of Hunslet, and also had a 
Technical School of Art in Park Square, Leeds. 

* Builder, 11 Quarry Mount, Hyde Park, Leeds, England. 

July, 1931] CAREER OF L. A. A. LE PRINCE 63 

He said that he required some woodwork which must be very accurately made, 
and it was given to me to carry out. During the next 2 1 / t years I was engaged 
almost continuously for Mr. Le Prince. I made all the woodwork and the 
patterns for metal castings. 

I discovered that he was constructing apparatus for the purpose of taking 
photographs in rapid succession and projecting them on a screen, so as to give 
the illusion of motion; in other words moving pictures. 

Mr. Le Prince equipped a workshop at 160 Woodhouse Lane, now occupied 
by the Auto Express Company, on which a bronze memorial tablet was un- 
veiled by the Lord Mayor of Leeds on December 12, 1930. 

At this unveiling the camera which Miss M. Le Prince brought from New 
York was shown, and this I at once identified as the one I assisted to make and 
which was completed about the summer of 1888. It was constructed to scale 
drawings made by Mr. Le Prince; he was a very clever draughtsman. The 
metal parts were cast at Whitley Partners and machined and fitted by Mr. 
J. W. Longley, who was the mechanic of Mr. Le Prince. 

The camera has two lenses, one being for taking the photograph and the other 
for the view finder. The gate mechanism behind the lens is constructed to hold 
the film firmly in position during exposure, and then to momentarily release it 
while being drawn upward without it being scratched. The intermittent 
movement consists of a toothed cam which engages with a projection on the 
side of the top reel, the latter pulling the film through the gate and also winding 
it up. 

The handle projecting from the side of the camera operates the mechanism 
through gear wheels. A brass shutter revolves in front of the lens which has in 
it an adjustable diaphragm. Turning the handle at the proper rate enabled 
pictures to be taken at the desired speed. 

For his cameras Mr. Le Prince used sensitized paper film and gelatin stripping 
film. Miss Le Prince brought along with the other apparatus a reel of the 
paper film which was found in the camera. 

In the early autumn of 1888 the camera was used for photographing a series 
of pictures, at about 12 per second, in the garden of Mr. Joseph Whitley, father- 
in-law to Mr. Le Prince. In them Mrs. Joseph Whitley is shown, and as she 
died on 24th October, 1888, this conclusively shows that the series was taken 
before that date. 

Another series, taken about the same time, but at a higher speed, was from a 
window of Hick Brothers, Ironmongers, from whom he had purchased tools 
and materials. Their premises are at the southeast corner of Leeds Bridge, 
and the pictures showed very clearly the moving of traffic across the bridge. 

Mr. Le Prince found the construction of the projecting machine much more 
difficult than the camera; it evolved through several stages, and when making 
changes existing parts were re-used as much as possible. One projector had 
three lenses, and was like a sketch of Mr. J. W. Longley's which he sent to Mr. 
Adolphe Le Prince in 1898, a photostat copy of which is in my possession (Fig. 7 

As indicated in his patent specification, Mr. Le Prince first dealt with the 
positive pictures by mounting them on bands, one material that he used being 
thin red fiber. Small holes were punched along the edges of the bands to engage 
with pins in the sprocket wheels. 

64 E. KILBURN SCOTT [J. S. M. P. E. 

In his earlier experiments Mr. Le Prince used oxy-hydrogen lime-light, but 
when finally he was able to get quick enough movement of pictures to employ 
only one lens, then he decided to have an arc lamp. This involved installing 
an electric generating plant, and he called in the assistance of his friend, Mr. Wilson 
Hartnell, electrical engineer, who lived close by in Blenheim Terrace. 

He supplied a dynamo and arc lamp, and his men installed them and ran 
cables over the roofs of intervening buildings from our yard at 150 to the work- 
shop at 160 Woodhouse Lane. 

The dynamo was driven by belt from our semi-portable Robey engine and 
boiler, which I operated at night. I have reason to remember the first time 
because Mr. Le Prince sent round that he wanted a higher voltage, and I took 
the risk of placing extra weights on the safety valve in order to get more speed 
on the dynamo. 

When the arc lamp was first switched on there were present, besides Mr. Le 
Prince, Messrs. J. W. Longley and Walter Gee, the last-named being an elec- 
trician for Mr. Hartnell. He is now chief engineer to the Barnsley Co-operative 
Society. They were the first people to see moving pictures projected with the 
arc lamp illumination, but afterward a few others had an opportunity, including 
Mr. Hartnell .and my brother William; the latter said the pictures showed well 
except for some flickering. 

It is important to note that details of the camera and projector with which 
Mr. Le Prince did his best work in Leeds departed considerably from those 
shown in his British patent No. 423 of 1888 and his United States patent serial 
217,809 of 1886. It was his intention to take out further patents, and naturally 
he was therefore reluctant to show his machines. 

Miss Le Prince brought back with the camera, etc., two long reels which her 
father had built up of strips, each about 3 inches wide and a foot long, fastened 
together and having silver along the edges to keep the layers apart. These he 
used for developing films. 

At a later date, long reels of somewhat similar material, sensitized and nearly 
transparent, became available. It would be in the early autumn of 1889 that 
Mr. Le Prince came to me in high spirits to say he had obtained some rolls of 
sensitized film called celluloid. As these were too wide I cut them in halves on 
a lathe, working with a red lamp at night. The incident is clear in my mind 
because I had to wait until it was dark, about 9 P.M. 

The coming of celluloid film solved the last difficulty, and in the spring of 
1890 Mr. Le Prince decided to go to New York, where his wife and family were, 
to show moving pictures there. He ordered from Mr. Trinder, a maker of port- 
manteaux in Woodhouse Lane, special cases to hold the apparatus. The cases 
which Miss Le Prince brought back were the originals with the maker's name 
still on them. 

Before sailing he went to France to see about patent business, also to bid adieu 
to his brother, an architect and engineer of Dijon, who saw him off at the station 
en route for Paris on 16th September, 1890. Unfortunately, from that moment 
he disappeared completely and, although exhaustive enquiries were made by 
detectives and members and friends of the family, no clue was ever found. 

After waiting about a month, Mr. Longley and myself entered the workshop 
and found everything quite normal, the machines intact, and tools, drawings, 

July, 1931] 



photographs, as well as a quantity of discarded material, lying about. Mr. 
Richard Wilson, a friend of the family and manager of Lloyds Bank, I. 
took charge of all the effects and proceeded to dispose of such parts as could 
readily be sold. 

A large tripod I made for the camera passed into the possession of Mr. Charles 
Pickard, photographer, of Leeds, who showed it at the unveiling ceremony. I 
picked up a few relics, and am sorry now that I did not secure some exposed 

In conclusion I would say that L'r. Le Prince was in nany 
ways a very extraordinary man, apart from his inventive genius, 
which was undoubtedly great. He stood 6 ft. 3 ins. or 4 in*. in 
his stockings, well built in proportion, and he was most gentle 
and considerate, and though an inventor, of an extrer.el. placid 
disposition which nothing appeared to ruffle. 

SIGNED by the said Frederic Mason) 
in the pres|n<SL,e o. 

SUBSUHIBSl, AKD SYfORM to before r.e, by Frederic 
this twenty-first day of April, 1931. 



FIG. 8. Signatures and witnesses to declaration by Frederic Mason. 

films and the drawings, as unfortunately nothing was done to preserve them. 
That they might have historical importance was not appreciated. 

Mr. Wilson retained the camera, parts of the projector, including a le 
above-mentioned reels, and a machine with multiple lenses that Mr. 
made in Paris in 1887 for the purpose of "proving his patent." 
went to Mrs. Le Prince in New York City, and were kept there t 
1930, when they were brought back to Leeds by Miss L 
housed in the Science Museum, South Kensington, London. 


In conclusion, I would say that Mr. Le Prince was in many ways a very extraor- 
dinary man, apart from his inventive genius, which was undoubtedly great. 
He stood 6 ft. 3 in. or 4 in. in his stockings, well built in proportion, and he 
was most gentle and considerate and, though an inventor, of an extremely placid 
disposition which nothing appeared to ruffle. (See Fig. 8.) 


Signed by the said Frederic Mason in the presence of 

Frances R. Outhwaite 

461 Bolton Villas, Bradford 

Subscribed and sworn to before me, by Frederic Mason, 
this twenty-first day of April, 1931. 

(Signed) GEO. L. FLEMING 
[ Seal ] GEO. L. FLEMING 

Vice-Consul of the United States 
of America at Bradford, England 


Summary. This report of the Progress Committee covers the period October, 

1930, to May, 1931. The important advances in the cinematographic art which are 
described are classified as follows: (I) Production, (2) Distribution, (3) Exhibition, 
(4) Applications of Motion Pictures, (5) Color Photography, (6) Amateur Cine- 
matography, (7) Statistics, (8) Publications and New Books. 

Although no epoch-making discovery was made during the past 
six months, there has been an evident improvement noted in all 
branches of technical endeavor in connection with sound recording, 
processing of records, and sound reproduction. Ever since the 
showing of the first successful feature sound picture in October, 
1927, the quality of sound reproduction has been gradually improving. 
The reproduction of sound reached a high level of perfection during 
the past winter, due to the introduction of methods for eliminating 
ground noise in both variable density and variable width recording. 
Equally significant were the marked improvements noted in the 
speed and color-sensitiveness of panchromatic emulsions. 

To facilitate the recording of sound under difficult studio con- 
ditions as well as to secure high-quality pick-up at a greater distance 
from the source, a microphone having directional pick-up was 
devised. Microphone concentrators, announced in the previous 
report, have found extensive use. An increase was also noted in 
the use of truck shots, both from small portable "dollys" as well 
as from more elaborate towers or camera parallels. 

Noteworthy changes in camera design were made which minimize 
noise and made unnecessary the use of "blimps" or sound-proof 
coverings except for close-up shots. Aluminum housings for in- 
candescent lighting equipment were claimed to have improved the 
portability of such units and to have eliminated the noise which 
commonly attends the warming up of lighting equipment. 

Further data were accumulated both by individuals and com- 
mittees on the important problem of acoustics of sound stages and 
theater auditoriums. Most major producing organizations in the 
United States recorded sound on film exclusively, re-recording on 

* May, 1931, Report of the Progress Committee. Presented at the Spring, 

1931, Meeting at Hollywood, Calif. 



disks when necessary for release purposes. Recording of pictures 
in France, England, and Germany settled down to a routine practice. 
Equipment for recording was installed in Italy, Russia, Japan, 
India, Brazil, and other countries. 

Laboratories were faced with the problem of improving their 
processing methods in order that all the benefits to be derived from 
the introduction of "noiseless recording" might be realized. The 
construction of several new laboratories was either completed or 
well under way. The latest modern types of developing machines 
and inspection equipment were installed. An increasing demand 
was felt for greater care in previewing release prints. 

Several subcommittees of this and other societies initiated the 
examination of the important aspects of projection, such as design 
and maintenance of projection rooms, screen illumination, monitoring 
and control of sound, and improvements in projection design. Fur- 
ther refinement in projector arc carbons was noted. 

Although significant progress was made in a method of realizing 
stereoscopic pictures, one authority considered that much research 
will be necessary before the process will have practical value. The 
applications of sound pictures continued to multiply as government 
bureaus, business organizations, and pedagogical institutions began 
to use this new medium of expression. Although additional im- 
provements were made in connection with methods of televising 
pictures, it was pointed out that a fundamentally new principle 
must be discovered in order that such processes may enjoy universal 

Few color pictures were made during the past six months and 
exhibitors came to believe that color must be regarded only as an 
adjunct to the technical refinement of the picture, as, in its present 
form, it has been shown to lack real box-office value. Faster emul- 
sions with better color-sensitiveness, coupled with improvements 
in processing, strongly indicated that subtractive processes would 
measure up to this requirement. The need for a satisfactory, in- 
expensive, three-color process still prevails and the announcement 
that a process is being developed by a leading American producing 
organization is encouraging. 

Other than the introduction of a few new models of cameras, 
projectors, and accessories, the most interesting development in 
amateur cine* equipment was the announcement of a paper film for 
sound recording and reproduction. 

July, 1931] PROGRESS REPORT 69 

The fertility of inventive minds was indicated by the relatively 
large number of patents issued in almost all the fields of motion 
picture technology during the past six months. 

Acknowledgment. Useful material for this report has been supplied 
by N. D. Golden and H. Griffin. A short article describing the- 
Selenophone process was prepared by P. von Schrott, a member of 
the Committee residing in Vienna, and has been recommended to 
the Papers Committee for publication. Data prepared by A. 
Garrels, U. S. Consul General at Tokyo, was considered especially 
interesting and has been edited as an appendix to the report. Several 
reports containing pertinent information were furnished by L. 
Cowan of the Academy of Motion Picture Arts and Sciences. 

Illustrations were supplied by the following companies: Con- 
solidated Film Industries, Hollywood ; Nela Lamp Works, Cleveland ; 
RCA Photophone, Inc., N. Y.; and Radio Pictures, Hollywood. 
A number of illustrations from current Indian productions were 
furnished by the following: Imperial Film Company, Bombay; 
Three Krishna Film Company, Bombay; and Prabhat Film Com- 
pany, Kolhapur City, India. 

Respectfully submitted, 








A . Films and Emulsions 

1. New Materials 

2. Manufacture 

3. Miscellaneous 

B. Studio and Location 

1. General 

2. Lenses and Shutters 

3. Cameras and Accessories 

4. Exposure and Exposure Meters 

5. Studio Illumination 

6. Actors and Direction Technic 

7. Trick Work and Special Process Photography 


8. Methods of Recording Sound 

9. Set Construction 

C. Laboratory Practice 

1. Equipment 

2. Photographic Chemicals and Solutions 

3. Processing Technic 

4. Printing Machines and Methods 

5. Tinting and Toning 

6. Editing, Splicing, and Titling 

7. Cleaning, Reclaiming, and Storage 


A. General Projection Equipment and Practice 

1. Projectors and Projection 

2. Sound Picture Reproduction 

3. Projector Lenses, Shutters, and Light Sources 

4. Fire Prevention 

B. Special Projection Methods 

1. Effect Projection and Stage Shows 

2. Portable Projectors 

3. Stereoscopic Projection 

4. Non-intermittent Projection 

C. Theater Design and Installation 

1 . Screens 

2. Theater and Stage Illumination 

3. Theater Acoustics and Construction 


A. Education, Business, and Legal Records 

B. Medical Films, Radiography, and Cine Photomicrography 

C. Television 

D. General Recording, Miscellaneous Uses 

A . General 

B. Additive Processes 

C. Subtractive Processes 

A . General Equipment and Uses 

1. Cameras 

2. Projectors 

July, 1931] PROGRESS REPORT 71 

3. Accessories 

4. Films and Film Processing 

B. Color Processes 


A. Films and Emulsions 

Concurrent with the general decline of business, which began 
late in the fall of 1930 and prevailed throughout the spring of M).'il, 
there was an abandonment of the wide-film program by the producing 
organizations. 1 Cost of installations in the face of a business de- 
pression and insufficient public interest in wide pictures were two 
probable causes of this decision. Larger screens were installed, 
however, in a number of theater circuits. Warrenton 2 suggested 
exposing the picture in a 3 by 6 rectangle in the area occupied by 
one frame on 35 mm. film, retaining the principle action in a 3 by 4 
area in the center of the longer rectangle. Prints could be made of 
the wide picture, or the smaller area could be printed optically to 
fill the entire frame. 

The Standards and Nomenclature Committee, however, reported 
at the October, 1930, meeting of the Society that the only satisfactory 
method of obtaining a large screen picture seemed to be by using a 
wider film. A plan is being studied which will permit the use of 
a 1.8 to 1 ratio for the picture size, a wider sound track, more suitable 
margins, and a film width intermediate between 70 mm. and 3o mm. 
Two symposiums on methods of securing a large screen picture have 
been held by the Society in New York, one in October and one in 
December, 1930. At the last meeting pictures made on 65 mm. 
film by Paramount were shown, the picture frame having a ratio 
of 1.78 to 1. Several meetings dealing with this subject were also 
held on the West Coast under the auspices of the Technicians' Branch 
of the Academy of Motion Picture Arts and Sciences. 

One of the most important developments for many years was the 
introduction of panchromatic emulsions of increased speed and im- 
proved color-sensitiveness, particularly in the red and green regions 
of the spectrum. With these ultra-sensitive materials, exposures 
may be made under more difficult conditions of illumination than 
with former emulsions or a better definition and depth of focus may 


be secured by stopping down the lens. Such emulsions offer great 
promise in color photography where the difficulties of obtaining 
sufficient exposure have long been recognized. Greater care must 
naturally be used in handling these faster stocks both in the camera 
and in the processing laboratories. The industry is proceeding 
cautiously in using them, in order that the cameramen and techni- 
cians may have an opportunity to understand their characteristics. 

Huse and Chambers 3 have published sensitometric data on East- 
man Super-Sensitive Panchromatic film, showing it to be about 
twice as fast to daylight and three times as fast to incandescent 
light as previous panchromatic emulsions. The properties of 
Du Pont Special Panchromatic negative film have been discussed 
by White. 4 It is stated that set illumination may be reduced 40 
to 60 per cent with this product. Filter factors are correspondingly 

Faster emulsions for sound recording work have also been intro- 
duced, to replace the relatively slow positive film in common use. 
The saving of lamp current in sound recording is a vital problem, 
especially on location, as any reduction in the number and required 
capacity of storage batteries adds to the mobility of sound recording 
equipment. A negative sound emulsion is desired that would re- 
duce present lamp current requirements about 50 per cent. 

The practice of duplication of all valuable negatives is increasing. 
According to present technic, master positives are made on a lavender 
base positive emulsion, and the duplicate negative on an especially 
fine-grain, yellow-dyed emulsion, particularly made for duplication. 

Paper emulsions were used in the Selenophone process for sound 
reproduction prints on amateur cine apparatus. 

Several patents have been issued relative to improvements in 
film support and emulsion manufacture. Five of these deal with 
sound film emulsions having a tinted support. 5 

Plans for the establishment of a factory at Elstree, England, to 
manufacture cellulose acetate base were announced in December, 
1930. 6 The increased use of industrial and educational films is 
creating greater demands on the manufacturers of this type of film 

A much smaller production of feature pictures in color was evident 
during the past six months than in the previous year, but trade 
reports indicated that there was an increased use of color for short 
features. Two industrial pictures were made by the Multicolor 


bi-pack process. Another bi-pack process called "Magnacolor" 
was announced. 7 (See description under section on "Color Photog- 

A direct color process claimed to be applicable to motion picture 
film was announced as being available for exploitation in Germany. 
Colloidal silver emulsions are used which are developed in a closed 
container with the vapors of formaldehyde, ammonia, and alcohol. 8 

Originals and copies on horizontally embossed film by the Keller- 
Dorian process were exhibited by Paramount at a meeting of t he- 
New York Section in December, 1930. 9 

Some measure of the resistance of exposed but undeveloped 
photographic films to the action of water, snow, and ice was shown 
when the last camp of Andree was discovered on White Island in 
August, 1930. The films had been lying there since 1898. Pro- 
fessor J. Hertzberg of the Royal Technical University, Stockholm, 
Sweden, developed them and found that 50 of the 192 exposures 
contained traces of the image; twenty made satisfactory pictures 
when processed, thirty-three years after being exposed in the camera. 10 

B. Studio and Location 

Refinements in methods of sound recording represented the most 
significant advance in American studio practice during the winter 
of 1930-31. Production in most of the European studios had 
settled down to routine work. In some of the more remote places 
in the world, sound recording equipment was still rather crude or 
entirely lacking, as, for example, in South Africa, South America, 
China, and India. In the last-named country the first native pro- 
duced sound feature was scheduled for release in March, 
Data on recent progress in Soviet Russia was somewhat meager; 
a paper by Monosson presented at Washington in May, 1930, and 
a later article by Moshonkin, constituting the most reliable sources 
of information. 11 

Lenses and Shutters. Dubray 12 has discussed the color correction 
of objective lenses, reporting that achromatizing at the C and G 
lines of the spectrum gives better performance than the usual photo- 
graphic correction. Lenses computed to this specification have 
been marketed. The depth of field of optical systems has been 
analyzed by Hardy, 13 who applied the results to the different methods 
of realizing large screen pictures. It was shown that the greatest 
depth of field results, for the same final screen magnification, when 

74 PROGRESS REPORT [J. s. M. p. E. 

the focal length of the camera and projector lenses are kept as short 
as possible. 

A new anastigmat of //2.8 aperture, made by Carl Zeiss, Germany, 
supersedes the older //2.7 lens. It is claimed to give uniformly 
good definition at all apertures. 14 

Only a few patents were issued on lenses and shutters and of these 
the majority dealt with minor improvements in shutters. 15 

Cameras and Accessories. The bulky, heavy "blimps" or sound- 
proof housings for cameras are gradually being displaced by in- 
sulation within the camera body itself. Many improvements have 
also been made in silencing the actual mechanism of the camera. 

Nearly 80 per cent of the inherent noise of the usual Bell & Howcll 
camera shuttle movement was claimed to have been eliminated 
by removal of part of the back register leaf so that four steel wires 
actually move the film on and off the pilot pins. 16 A novel camera 
construction from the Warner Brothers studios had its first public 
showing in October, 1930. According to Stull, 17 features of the 
new camera are an enclosed movement and a lens which moves 
only in a horizontal plane during focusing by making the entire 
turret movable. 

The Fearless Camera Company recently perfected a new camera 
which is adapted for use either with 35 mm. or wider film up to 50 
mm. No housing is required for all average camera work and the 
cameraman may use it for recording sound directly in the camera 
if so desired. Other features are (1) a new type magazine which 
is easily threaded, is very free-running, and is stated to eliminate 
trouble from film jamming, and (2) an adaptor holding two ordinary 
magazines as used in bi-pack color photography. 18 An improved 
Debrie camera fitted with a synchronous motor has been described 
briefly. 19 

During the last six months, there has been a marked increase 
in truck shots in which the camera is mounted on a "dolly," or 
perambulator, which is moved with or around the action during 
the progress of a scene. The director, in one sense, edits the picture 
on the stage during actual production. Great precautions are 
taken to avoid noise when the truck is moved. In some instances 
the microphone boom is mounted on the truck with the camera, 
but as a rule microphones are manipulated from a separate position. 
Sometimes two or three booms are necessary to cover the sound 
during a long scene. 

July, 1931] 



In making Cimarron, The Lady Refuses, and several other pictures, 
a more elaborate truck was found useful (Fig. 1). Parts of an 

FIG. 1. Special camera parallel and truck. 
(Reproduced by courtesy Radio Pictures, Inc., Hollywood.) 

automobile chassis were used in its construction. A central tower 

was built which could be raised to a height of 23 feet. 

platforms were also available so that the truck accommodated 


about six people, two cameras, a microphone reflector, and other 

Numerous patents on improvements in camera design have been 
issued. 20 A few patents were granted on cameras for taking pictures 
having stereoscopic effects. 21 Non-intermittent movements in 
cameras were also protected by patents. 22 Patents were issued 
covering a variable film feed mechanism, a camera for taking pictures 
in a spiral arrangement on a transparent disk, and a process for 
motion picture time studies involving control and numbering of 
the frames of the film. 23 

Exposure and Exposure Meters. Various methods, both practical 
and theoretical, for determining filter factors have been discussed 
by Chibissoff and Michailowa. 24 Dubray 25 has described an ex- 
posure meter which measures the adaptation level. The instrument 
was devised by Norton. A method of determining exposure, worked 
out by Loveland, 26 consists in developing, in a rapid working solution, 
a trial exposure on a strip of film which previously has had a sensito- 
metric exposure on a separate area from the picture. Comparison 
of two or more densities of the picture and of the graded strip gives 
a measure of the exposure. 

Studio Illumination. One of the outstanding developments in 
studio lighting equipment during the past six months was the pro- 
duction of silicon-aluminum housings designed particularly to 
eliminate the objectionable noises commonly given off by the older 
sheet-iron housings when a lamp is warming up. An unequal ex- 
pansion occurred in the older type lamp between the inner and 
outer sheet-iron housings over a cast-iron frame. Several manu- 
facturers have produced this solid aluminum equipment of which 
some designs are made of four casings bolted together, and others, 
of a single large unit. Common sizes in use are an 18-inch unit 
for a 2000-watt lamp and a 24-inch unit for the 5000- watt lamp. 
When it is undesirable to increase the number of 1000-watt or 
1500-watt units, large reflector types are used, fitted with 5000- 
watt, 11 5- volt lamps which distribute their radiation over an angle 
of 25 degrees. 

Lamps employed for studio work have been strengthened greatly 
to make them more resistant to rough treatment. The use of heat- 
resisting glass has greatly reduced the tendency for discoloration 
and has improved the ability of the lamps to withstand high tem- 

July, 1931] PROGRESS REPORT 77 

Arc lamps of German manufacture and accessories for the elimi- 
nation of arc noises were described by Korting and Matthiesen. 27 

Actors and Direction Technic. According to U. S. Department 
of Commerce trade reports, a British college for training actors 
has been inaugurated. The course lasts nine weeks and includes 
deportment, stage acting, elocution, and make-up. 28 Universal 
Pictures are stated to be planning a practical training school for 
actors which will include instruction in sound recording, costuming, 
set design and construction, make-up, and actual acting before the 
camera. Griffith 29 has been granted a patent on a method of intro- 
ducing peculiar light and shadow effects by interposing a semi- 
transparent screen between the camera and the player. 

Trick Work and Special Process Photography. In the making 
of a well-known type of sound cartoon, the sound score is prepared 
first and the scenario is then written under the score. The number 
of sketches for each musical note is calculated. A staff of 20 artists 
prepare about 5000 pen and ink sketches for each release, working 
about one month to complete a picture requiring only 6 minutes for 
projection. 30 

Patent protection was granted on a method of preparing a cartoon 
film for subsequent synchronization with an existing sound record film, 
as well as on a process for making composite pictures in which two 
objects at different distances and in different directions are photo- 
graphed on the same film. 31 Pomeroy 32 has disclosed a process 
for producing composite photographs embodying two component 

Sound Recording. According to Knox, 33 the problems of the 
sound engineer are: (1) extension of the frequency range of recording 
and reproducing equipment; (2) increasing the volume range so 
that fainter and louder sounds can be recorded and reproduced; 
and (3) reducing ground noise to a minimum. Lichte* 4 has dis- 
cussed in a general way the problems of sound recording associated 
with German equipment, laying particular stress on the underlying 
causes of distortion. Dreher 38 has reviewed recent progress in 
sound recording both by variable density and variable width proc- 

A most significant improvement in the quality of sound reproduced 
from variable density records has resulted from the introduction 
of the biased-valve method of recording by Western Electric. 
this method, ground noise has been reduced 10 db., according to 



[J. S. M. P. E. 

Silent. 18 An auxiliary circuit is associated with the light valve, 
and when the sound currents are small, the ribbons vibrate over a 
small amplitude. As the sound increases, the spacing between 
the ribbons is increased automatically by the auxiliary circuit. 
Thus, the sound print is darker for weak sounds and lighter for 
strong sounds. About forty features had been produced up to 

April, 1931, using this method of record- 
ing. Full benefit of the system can be 
derived only by proper development of 
the sound track and close cooperation is 
therefore necessary between the sound 
department and the processing labora- 
tory. The introduction of improved 
methods of recording has raised the 
question of reducing noises in theaters 
emanating from fans, ventilators, and 
projectors, and consideration is being 
given this question. 

Another method of reducing ground 
noise is described by Townsend, Clark, 
and McDowell for use in variable width 
recording. 37 A shutter in the path of 
the light beam is automatically moved 
to cut off as much light as possible, 
consistent with carrying the modula- 
tion. In principle, this scheme, like the 
Western Electric "Noiseless Recording" 
process, consists in rectifying a portion 
of the output of the recording amplifier, 
and using this current to keep the 
amount of light admitted to the film at 
a minimum. 

According to reports from the West 
Coast studios, the practice of re-record- 
ing by electrical means is increasing and 

the present tendency is to incorporate sound effects into the original 
sound track after it has been recorded and developed. It is often pos- 
sible by this method to shoot scenes without sound equipment and 
add the sound effects later in the dubbing process. Loss of quality in 
re-recording which may be partly attributed to defects in dubbing 

FIG. 2. Directional pick-up 


(Reproduced by courtesy 
RCA Photophone, Inc., N. Y.) 

July, 1931] PROGRESS REPORT 79 

machines has been greatly reduced by improvements in such ap- 

A new type of microphone, for which directional pick-up character- 
istics are claimed, has been developed by RCA Photophone 88 (Fig. 2). 
The operation of the microphone depends on the induction of elec- 
tric currents of audible frequency in an extremely thin and light 
corrugated aluminum ribbon, placed between the poles of an electro- 
magnet, and caused to vibrate by the acoustic wave. Sounds 
normal to the face of the microphone are picked up whereas sounds 
at angles to the normal are received very feebly if at all. It is 
possible to secure high-quality pick-up at a greater distance (usually 
about double) from the source than with a condenser type micro- 
phone. When used on microphone booms, the amplifier associated 
with the microphone is removed to reduce the carrying weight. 

Details of construction and advantages of the use of microphone 
concentrators were treated by Dreher 39 at the fall meeting of the 
Society in 1930. High-quality sound pick-up is made possible at 
distances of from 20 to 40 feet and concentrator microphones are 
finding extensive use for outdoor work, particularly in conjunction 
with trucking shots. Improvements in carbon microphones for 
use in sound recording have been discussed by Jones. 40 The intro- 
duction of an air-damped, stretched diaphragm and a push-pull ' 
arrangement of two carbon elements has increased the fidelity of 

A description has been published by Kellogg 41 of a new recorder 
for variable width recording which employs a magnetic drive to secure 
uniform speed. In a power amplifier system described by Thomp- 
son 42 two tubes with matched grid-current vs. grid-voltage character- 
istics are used in a push-pull circuit. Vogt, 43 one of the inventors 
of the German Tri-Ergon method of recording sound, has dealt with 
the influence of the slit width on the accuracy of representation of 
photographically recorded sound frequencies. Both von Hartel 44 
and Livadary 45 have treated other aspects of this important subject. 

The matter of acoustically treating sound stages and theaters 
continued to ' receive active consideration. Linck 48 has reported 
the results of oscillographic studies of sound in several types of rooms. 
Interference effects caused by differences in time and position were 
examined by Kuntze 47 who used a circuit with two microphones to 
simulate binaural reception. On the West Coast, one of the equip- 
ment manufacturers has built an acoustic laboratory fitted to make 



[J. S. M. P. E. 

absorption and transmission measurements over a wider frequency 
band than has ever before been attempted (Fig. 3). 

The use of a third electrode in flashing lamps for recording by 
causing continuous ionization of the gas present, eliminates the 
hysteretic effect due to the difference between the ignition voltage 
and the extinguishing voltage. 48 Milkutat 49 has dealt with the 
subject of volume control, especially with regard to the effect of 
echo in the recording studio. 

FIG. 3. Reverberation chamber in acoustic laboratory. Panel to be tested 

is placed in opening between the two rooms. 
(Reproduced by courtesy Electrical Research Products, Inc., Hollywood.) 

RCA Photophone has designed a compact sound recording truck 
fitted with a monitoring and a recording compartment. 

Robillard and Lyford 50 have published details concerning recent 
developments in RCA portable recording equipment, such as the 
optical system, galvanometer, and amplifier. Studio equipment 
supplied by the same firm was described by Button and Read, 51 

July, 1931] PROGRESS REPORT 81 

the features emphasized being constant impedance mixing, a filter 
for eliminating low rumbles, and a recording amplifier with two 
output channels. 

The entire Tanar sound truck is insulated to serve as a monitor 
room, sufficient amplification being supplied for four microphones. 62 

As was foreseen, film recording is tending to replace disk recording, 
because of the greater ease of editing sound records on film and the 
introduction of methods of reducing ground noise, whereas disk 
recording affords little opportunity for further reduction in surface 
noise. All the major producing companies in the United States 
now appear to be making their original recordings on film. Re- 
recording is done when disks are required for release. 

A single string oscillograph is used in the Selenophone (German) 
method of recording, and the apparatus is so designed that eight 
ordinary sound tracks can be recorded side by side across the film 
width. A selenium cell designed by Thirring, a condenser type, is 
used as the light-sensitive element. The company has developed 
a method of recording on paper for use with amateur equipment. 63 
(See Section VI.) 

Various processes and equipment used in French studios for re- 
cording sound in conjunction with pictures have been described by 
Bonneau. 54 According to a report from India, sound pictures are 
becoming increasingly popular especially since recording equipment 
has become available. Three companies have recording equipment, 
and the first all-Indian feature picture scheduled for release in 
March was recorded in Hindustani, a step which may help to a 
considerable extent in unifying the 300 odd dialects at present 

A great many patents have been issued particularly in the United 
States and Great Britain dealing with improvements in processing 
of sound recording in conjunction with motion pictures. 66 

Set Construction. A material consisting of pressed fir and balsam 
wood has been developed to prevent loud reverberations on street 
pavements used in sound picture sets. 66 Sets for silent pictures 
were usually built of three-ply wood veneer, covered with wall- 
paper, or painted to give the effect desired. These materials cause 
reverberation which interferes with the fidelity of the sound pick-up, 
particularly on long shots. Thin unbleached muslin cloth, properly 
stretched, eliminates reverberation almost entirely and permits 
much greater flexibility in sound recording. It is often possible, 


with such sets, to take medium and close-up camera shots simul- 
taneously, using only one sound pick-up. 

Costly retakes are thus avoided and production expenses corre- 
spondingly reduced. A set made entirely of cloth is a rarity but it 
is not uncommon for cloth to constitute 75 per cent of the entire 
construction. Opaque material is used to back the cloth to prevent 
light from showing through and door frames must be carefully 
constructed to avoid transmitting vibrations to the cloth. 

C. Laboratory Practice 

Equipment. Since the advent of the sound picture, the technic 
of laboratory processing has improved considerably. The signifi- 
cance of sensitometry in relation to sound and picture quality 
is being realized more and more each year. Recent processes for 
reducing ground noise demand great care in developing the film. 
In the field of sensitometry there has been a tendency to concentrate 
on time scale devices rather than on intensity scale instruments. 
There is a need, however, for some agreement on a particular type 
of instrument so that comparisons between controls at various studios 
can easily be made. A diffuse reading densitometer designed by 
the Bausch & Lomb Optical Company has found application in 
three West Coast laboratories. Densities as high as 4.0 can be 
read with a high degree of accuracy. 

Two large processing laboratories were opened during the past 
six months in Hollywood, Calif., and two others are known to be 
under construction. 

Lob 57 has discussed the optical systems of a number of different 
types of photometers for making subjective density measurements. 
Four adaptations of the comparison microscope were considered 
by Conklin 68 at the Fall, 1930, Meeting of the Society. The action 
of photographic solutions on various construction materials with 
relation to their suitability for processing apparatus has been dis- 
cussed by Crabtree, Matthews, and Ross. 5J 

Only two patents were noted dealing with processing equipment. 60 

Photographic Chemicals and Solutions. One of the outstanding 
problems with regard to all film developing machines is that of 
maintaining a constant rate of activity of the developer. A paper 
by Crabtree and Ives deals with a replenishing solution for a motion 
picture positive film developer. Specific directions are given for 
replenishing when developing by the rack and tank system, and 

July, 1931] PROGRESS REPORT 83 

suggestions are made regarding the composition of the developer for 
machine development. 61 . 

Valenkov 62 has discussed the significance of the "Eberhard effect"* 
in photographic photometry and concludes that the effect has little 
significance in spec trophotome try, is independent of the form of the 
picture, and occurs chiefly in areas smaller than 3 mm. in diameter. 
Rzymkowski 63 has continued his work on the chemistry of develop- 
ment and has reported on the role of sulfite in developers. Fogging 
action of hydroquinone developers with low sulfite content is believed 
due to the formation of a mono-thiosulfonic acid derivative of 
hydroquinone. Crab tree and Matthews 64 have discussed the effect 
on processing of motion picture film of various impurities, dissolved 
salts, extracts, and gases sometimes found in the water supply. 

Processing Technic. Problems faring laboratories are: (1) a 
means of quickly measuring the developing activity of a bath or 
the gamma to which the film is being developed; (2) a method of 
maintaining the bromide concentration constant throughout the 
life of the solution and recovering this salt from the bath; and (3) 
a non-staining developer for the development of variable density 
sound film. 

General papers on sensitometric control of sound film processing 
have been published by Eggert and by Schmidt. 65 By impressing 
a sensitometric exposure on the beginning and end of a 1000-foot 
roll of variable width sound record film, according to Cooper, 660 the 
cameraman can tell the degree of development independent of the 
exposure by examining the developed strip. The sensitometric 
exposure is made by using a weak alternating current for operating 
the oscillograph recorder, and allowing the recorder to come to a 
stop after turning off the current. By measuring the developed 
densities at marked intervals and the distance between the wave 
peaks, the gamma may be calculated. 

An investigation has been started by a subcommittee of the 
Academy of Motion Picture Arts and Sciences on methods and 
standards to be followed in processing film. Formal recognition 
will be given to desirable standards on which there is general agree- 
ment. 66 

Light valve recording on the underexposure or "toe" portion of 
the characteristic curve is stated by Lewin 67 to be in use by Para- 

* An increase in density of a small area inside a larger area which has received 
less exposure. Most apparent with short development. 

84 PROGRESS REPORT [j. S. M. p. E. 

mount for scoring and playbacks. It is claimed to be less sensitive 
to development errors. A system of counter-current flow in ma- 
chine fixing baths is advocated by Landau. 68 

A patent has been issued for the use of a sound film having a latent 
image of a sensitometric strip printed at intervals throughout its 
length. 69 

Printing Machines and Methods. The applications of dubbing, 
as described by Lewin 70 are (1) re-recording of completed features; 
(2) re-recording of dialog to mix sound effects ; and (3) synchroniz- 
ing of foreign voices to a picture, more correctly known as "doubling." 
Tuttle 71 has designed a compounded Geneva pull-down for rngtion 
picture printers which is essentially a Lumiere cam mechanism 
running at high speed, provision being made for "idle strokes." A 
description of a semi-automatic sensitometer has been published by 
Crabtree, Ives, and Tuttle 72 in which the exposure intensity is equal 
to that in the motion picture printer. Stress is laid on the dependence 
of photographic quality on the intensity of the exposing light in a 

Goldschmidt 73 has described a photometer for calibrating printing 
lamps which employs a photo-cell and a precision torsion galva- 
nometer, reading directly in lux. A 4- volt battery supplies the 
necessary potential, low voltages being desirable in instruments 
used for this purpose. For printing "stills" in a German laboratory, 
a semi-automatic device is used. Two graduated filters may be 
moved simultaneously, one over the printing light and the other 
over a comparison lamp of fixed intensity. One-half of a matched 
field is illuminated by light which has passed through an average 
or important part of the negative and then through one of the filters, 
while the other half receives light from the comparison lamp through 
a second filter. A photometer which compares the extreme densities 
on the negative indicates the contrast grade of paper required. 74 

Improvements in printing equipment disclosed in patents include 
methods of printing sound film records. 75 

Tinting and Toning. Crabtree and Marsh 76 have worked out 
a method of double toning of motion picture film which consists 
in toning the image blue in the usual iron toning bath, fixing in 
hypo, washing, re-toning, and lastly, immersing in a basic dye 
solution. Only one patent has been noted on a method of coloring 
motion picture film. 77 

Editing, Splicing, and Titling. A growing demand exists for the 

July, 1931] PROGRESS REPORT 85 

inspection of every release print regarding its sound and picture 
quality. One type of film inspection equipment consists of a stand- 
ard Western Electric reproducer installed on a projector. The 
lower magazine is cut away to allow the film to be pulled back for 
hand inspection. Sound is picked up by a caesium cell and fed into 
an amplifier having an output ample for headset monitoring; with 
additional amplification, standard theater horns may be used. A 
sound head made by Vinten is being used in England for examining 
the quality of release prints. 78 In the Universal Laboratory, Holly- 
wood, a final description of each release print is prepared by a stenog- 
rapher who types the titles and identity of the successive scenes 
as the picture is projected on a small glass screen before her desk. 79 

A limited number of patents has been issued covering improve- 
ments in editing and splicing. 80 The introduction of sound pictures 
has greatly reduced the need for titles, as is apparent in the scarcity 
of patents on this subject. 81 

Cleaning, Reclaiming, and Storage. Changes in the design of a 
well-known buffing machine for cleaning film have been described 
by Dworsky. 82 Patents issued include methods of waxing, humidi- 
fication, surface protection, and elimination of scratches and abra- 
sions on motion picture film. 83 


According to the Annual Report of the Academy of Motion Pictiuv 
Arts and Sciences prints released during 1931 by practically all of 
the Hollywood studios will be prepared according to uniform speci- 
fications designed to facilitate threading, precision change-over, and 
exact synchronization . 84 

An interesting commentary on distribution problems appears 
in a report prepared by D. G. Clark, Assistant Trade Commissioner 
of the U. S. Bureau of Foreign and Domestic Commerce, residing in 
Johannesburg, South Africa. Because of the great distances between 
centers of population and the limited size of the usual theater audi- 
ence, at least one-third of the distribution "life" of an average 
feature is consumed by transportation. 86 


The first of a series of small theaters was opened in March in 
New York City. For a small admission charge, the patron may 
witness the picture as projected on a daylight screen by rear pro- 


krtion. 88 A theater catering exclusively to children and seating 
over 1400 was opened in November, 1930, in Jersey City, N. J. 
Three performances are given daily; at 9.30 A.M., 2.00 P.M., and 
4.00 P.M. There are no evening or Sunday performances. 87 

Pictures with several song inserts appeared to have lost their 
appeal to theater patrons during the past half year. American 
audiences have been trained to expect reality and the novelty of 
hearing a singing chorus with orchestral accompaniment in a desert 
scene soon wears off. In several of the sound pictures released 
during the early part of 1931 an evident effort was observed to 
reduce the amount of dialog, song, and dance, and to increase the 
sound effects in order to enhance the action. 

A . General Projection Equipment and Practice 

Practically an instantaneous change of lenses was stated to be 
possible with a new front plate assembly for the Powers projector. 
Other modifications are a lens centering device, a micrometer focus- 
ing pinion, a framing lamp, and an aperture change assembly. 88 
According to an announcement in the German publication, Die 
Kinotechnik, the shutter on the Bauer M-7 projector is now arranged 
in front of the condenser lens in accordance with recent projector 
construction practice. 89 Descriptions of the Hahn II, Ernemann 
II, and Ernemann III projectors, all of German manufacture, have 
been published. The last-named projector has a lens mount capable 
of carrying lenses of 80 and 100 mm. diameter, thus permitting an 
aperture of //1. 9 to be used on lenses of almost any focal length. 90 

Features in the design of the Oemichen projector for Ozaphane 
film are: multiple tooth intermittment pulldown claws, low tension, 
separately adjustable gate shoe pressure springs, and friction rollers 
to assist feed and hold-back sprockets. These features are claimed 
to permit as many as 40,000 successive projections of a strip of 
film before it is worn out. 91 

Patent protection was granted on a considerable number of ideas 
relative to projector equipment and operation during the past six 
months. 92 

Sound Picture Projection. The use of a separate projector for 
reproducing sound was initiated in a London theater, the Pavilion, 
in November, 1930. It is stated that this is the first time such a 
scheme has been utilized in a British theater. 93 For preview service, 
in Hollywood, one company has provided two portable dummy sound 

July, 1931] PROGRESS REPORT 87 

projectors. These are installed in the theater and coupled to the 
regular projector before the preview. This permits the studio to 
have a preview of a production using the assembled intercut prints 
of both picture and sound track and eliminates the necessity of 
making a sound print which usually requires cutting after the pre- 

A rotating disk instead of the usual friction gate is used to control 
film movement in a new type of sound projector. 94 A sound-film 
projector, suitable for theaters seating not more than 1000 persons, 
has been marketed. It is designed to operate on 110 volts, 50 to 
60 cycles. 95 This equipment is one of several less expensive high- 
quality projectors for either film or disk records now available on 
the American market. 

Sound reproducing equipment is being manufactured by a British 
firm which uses a magnetic coupling between the projector and the 
turntable. A single photoelectric cell is placed centrally between 
two projectors. 96 In another British sound apparatus, the photo- 
electric cell and amplifier unit are mounted on a chassis which may 
be inserted in the projector or removed quickly in case of failure 
of the unit. 97 

Difficulties encountered in equipping automobile sound-film 
projection units are discussed by Bull. 98 The lay-out and installa- 
tion of a typical truck for outdoor projection is described. Natebus" 
has published a description of the Friess sound-film projector. The 
starting of the projector and fading are accomplished automatically 
by means of the film strip itself. The film is inserted in the pro- 
jector for a change-over without regard to synchronization. Metallic 
contacts on the film then successively actuate relays which lower 
the needle into the proper groove, close the fader circuit, and ex- 
tinguish the light in the first projector. Provision for automatic 
volume control is made and one type of equipment uses two disks, 
one above another. 

In the Projectophone devised by Mihaly 100 the sound track image 
is projected by a suitable optical system onto the photo-cell located 
at some distance from the projector. If the detector is located at 
one side of the main projection screen, the advantage claimed is 
that it obviates the need of wiring between the projection booth 
and the screen and there is no risk of extraneous noise being intro- 
duced from generators. A caesium photo-cell is used. 

The importance of periodically checking up the performance of 


the sound equipment has been stressed repeatedly by writers in 
the trade publications. The paper by Wolferz is of interest, there- 
fore, as it deals with a portable test set for measuring voltages 
testing circuits, amplifier and rectifier tubes, etc., on any sound 
projector installation. 101 

Many theater stages have insufficient space backstage for a horn 
installation for sound picture projection. For such theaters, as 
well as for any theater where only a limited space is available for 
the loud-speaker installation, a shallow horn has been introduced 
by the Western Electric Company (Fig. 4). The horn is provided 
with twin air columns which meet in a common mouthpiece. The 
equipment is 26 inches deep, 107 inches wide, and 62 inches high. 102 

A super-electrodynamic speaker was described at the Fall, l()o(), 
Meeting of the Society by Serge, 103 who emphasized the importance 
of the acoustical coupling between the loud speaker and the audi- 
torium. A valve controlling the flow of compressed air into the 
small end of an exponential horn was introduced in a new type of 
reproducer as a useful asset to loud-speaker performance. 104 

Problems arising during synchronization of sound and picture 
records, especially records in different languages, have been discussed 
by Thun who dealt with the new Organon method worked out by 
the German Polyphone concern for overcoming unnatural synchroni- 
zation. 105 

A rather detailed analysis of ground noise in relation to sound 
reproduction has been prepared by Tasker 106 who warns against 
vibrations in the recording equipment. Stryker 107 has shown 
experimental measurements of scanning losses under various test 
conditions to be in excellent agreement with those which would be 
anticipated from a theoretical study. The conclusion is drawn 
that with proper design and adjustment, optical systems need not 
be responsible for an appreciable loss of efficiency at the higher 
frequencies normally used in reproduction. 

Changes in sound reproduction caused by varying slit width 
have been considered by von Hartel. 108 Besides presenting formulas 
showing the relation between the sound intensity and the width of 
the slit, the paper gives data showing that halation causes overtones 
which consist especially of octaves. A mathematical analysis has 
been made by Frieser and Pister of the effect on sound reproduction 
of a finite slit width, inclination of the slit to the direction of motion 
of the sound track, and non-uniformity of illumination of the slit. 109 

July, 1931] PROGRESS REPORT 89 

Livadry 110 has treated the relative efficiency of different optical 
slits and their frequency characteristics in sound recording and 

Frediani 111 avoids the use of photo-cells in reproducing sound 

FIG. 4. Shallow type twin air column horn. 
(Reproduced by courtesy Bell Telephone Laboratories, N. Y.) 

from variable density records by passing them between electric 
contacts connected with the grid circuit of a thermionic amplifier. 
For such reproduction, paper prints may be used. 

Hatschek 112 has published equations for the design of pick-up 
arms for disk reproduction. 


A general paper giving details of photo-cell design has been pub- 
lished by Schroter. 113 A photo-cell made with cuprous oxide, ac- 
cording to another article, possesses high efficiency. 114 Roth 116 has 
dealt with recent developments in the Selenophone process which 
uses a selenium cell in connection with sound reproduction. 

Graham 116 estimates that 10 per cent of the population who can- 
not hear sound pictures satisfactorily will be able to benefit from 
the use of a theater hearing aid device which he described in a paper. 
Articulation vs. loudness curves are used to determine the amount 
of aid possible for any particular degree of deafness. 

Numerous patents were issued which disclosed improvements in 
sound reproduction equipment. 117 

Projector Lenses, Shutters, and Light Sources. The recent use 
of screen pictures of large size has led to the development of lens 
turrets on projectors with objectives of the desired focal length 
ready to be moved into position to suit the requirements of the 
program. 118 Lenses of anastigmatic quality have been applied as 
objectives for theater projection work, as reported by Rayton. 119 
Their aperture ratio of f/2.3 requires a special condenser system 
of large diameter if maximum screen illumination is to be secured. 
Schering has published a report on the efficiency of projection optical 
systems in ten German theaters, based on measurement of screen 
illumination. 120 

In a British process for securing a wide picture on the screen from 
35 mm. film, a pair of achromatic cylindrical lenses is used, one 
concave and one convex, the ratio of foci being in relation to the 
degree of expansion of the image desired. A pair of spherical lenses 
is placed in front of the achromats to correct for aberrations. A 
similar lens installation is used in the camera except that the optics 
are arranged to compress the images. 121 

To utilize all the beam issuing from the film aperture of a projec- 
tor using a mirror arc, Hauser and Mohr 122 conclude that the rela- 
tive aperture of the objective lens must be greater than that of the 
mirror, defined by the ratio of the diameter of the mirror to the dis- 
tance of its center from the film. 

A limited number of patents was issued dealing with projector 
lenses and shutters. 123 

It is generally considered that little trouble from eye-strain is 
experienced by normal persons viewing a motion picture in a theater 
where the projection is satisfactory. This is particularly true in 

July, 1931] PROGRESS REPORT 91 

the United States, but projection standards abroad are apparently 
not as satisfactory as they might be, as shown by the results of a 
questionnaire circulated among Italian school children, teachers, 
and eye experts. Thirty-three per cent of the children experienced 
eye-strain persistently or occasionally. For normal sight under 
good projection conditions, there should be no fatigue with shows 
of moderate length. 124 A British report suggests that a screen 
illumination of 7 foot-candles would be a feasible and suitable value. 
It is also proposed that the angle of elevation of the eye to the top 
of the picture should be limited to 35 degrees. 125 

Causes of variations in the light and steadiness of high-intensity 
carbons were discussed by Joy and Downes. 126 The demand for 
higher powered light sources in the theaters, using low-intensity 
reflecting arc lamps, has been met by the production of a higher 
current trim. This consists of a 13 mm. by 8 in. cored positive 
carbon and an 8 mm. by 8 in. cored negative. It is designed for 32 
to 42 amperes at the arc. Previously, 32 amperes at the arc was 
the highest attainable. The introduction of a pre-cratered high- 
intensity projector carbon was also noted. These carbons are 
supplied as 9 mm. by 20 in. and are said to burn more quickly and 

Dash 127 has discussed the most suitable way of connecting genera- 
tors for the operation of projection arcs. Naumann 128 has sum- 
marized methods for computing data on illumination in projection 

Three French patents were the only ones noted which dealt with 
projection light sources. 129 

Fire Prevention. Although no articles of significance were pub- 
lished during the past half year on the subject of fire prevention, 
the number of patents issued give evidence of the attention being 
given the subject by inventors. 130 

B. Special Projection Equipment 

Effect Projection and Stage Shows. During the presentation of the 
stage play Miracle at Verdun, at the Martin Beck Theater, New 
York, in March, 1931, sound motion pictures were combined effec- 
tively with the stage action. Three separate synchronized pro- 
jectors were used to project pictures on three screens arranged back 
stage in the form of a huge cross. Six horns were used behind the 
screens and others above the proscenium arch and at points in the 



[J. S. M. P. E. 

auditorium. 181 A patent covering apparatus for projecting a plu- 
rality of sets of motion pictures was issued. 132 

FIG. 5. Continuous portable sound-film projector. 
(Reproduced by courtesy Electronics and Auto-Cinema Corp., N. Y.) 

Portable Projectors. Two new types of portable continuous pro- 
jectors have been marketed, one for 35 mm. film and the other for 
16 mm. film. Approximately 400 feet of sound film can be ac- 

July, 1931] PROGRESS REPORT 93 

commodated on the 35 mm. projector (Fig. 5). Rear projection 
is used and the apparatus is entirely automatic. Only a few patents 
were noted which dealt with portable projectors and projection. 133 

Stereoscopic Projection. According to Taylor stereoscopic vision 
requires that two eyes, related physiologically and psychologically, 
each view separately, distinctly different pictures. Several available 
methods for independent left and right eye vision are discussed in 
this article. 134 

Considerable research has been conducted by Ives to devise 
cameras and projectors for the production of pictures showing relief. 
The results of some of this work have been published in recent issues 
of the Journal of the Optical Society of America. The method 
consists, essentially, of making a series of pictures from juxtaposed 
points around an object and projecting the prints from these onto 
a special screen. The requisite properties of the screen are (1) 
the light beams must be reflected directly back toward the projectors 
with no lateral spread, and (2) a vertical spread or diffusion should 
be introduced. Two types of screens having these properties have 
been developed, one made of vertical solid celluloid rods and the 
other of strips of mirror. 135 More recently a stationary camera 
requiring only a single exposure has been devised but Ives indicates 
that much additional research is needed to perfect the process. 186 

A limited number of patents, chiefly French, have been issued 
relative to stereoscopic projection. 137 

Non-intermittent Projection. Several interesting patents 138 have 
been issued on this subject recently but no articles of importance 
have been published. 

C. Theater Design and Installation 

Screens. As noted earlier in this report, wide screens have been 
installed in many theater circuits as an aftermath, perhaps, of the 
wide-film movement. A larger picture has certain advantages which 
exhibitors desire and it is a simple expedient to mask the screen 
down for smaller picture projection if the larger screen is not desired. 
In connection with one group of theater operations, the following 
table represents the screen sizes used for various projection distances, 
all the dimensions being in feet: 

Projection Distance 













A diffused border is favored in the masking of close-ups. Kreuzer 139 
has analyzed data for measuring light reflection and sound trans- 
mission characteristics of screens. A fire-resistant material for 
construction of motion picture screens has been announced which, 
it is claimed, will ignite with difficulty and will not propagate flame 
beyond the area exposed to the flame. 140 

A method of testing motion picture screens according to Little 
involves brightness measurements in two planes mutually perpen- 
dicular and perpendicular to the screen on which the incident beam 
is inclined at some angle above the screen axis. Tests of screen 
color in relation to the color of the light source are recommended. 141 

Three new types of screens have been described in the literature 
as being commercially available. A non-inflammable screen of 
rubber composition perforated with small holes was demonstrated 
in November, in London. 142 Another type of screen incorporates 
a cooling system for the theater. Behind the metal screen surface 
is located a refrigerating plant which causes the screen to become 
entirely coated with white frost. 143 In the third type, a non-glare 
and pseudo-relief principle is introduced. A pigment is used to 
cover the surface with a regular pattern which is claimed to absorb 
the harmful rays and reflect the remainder. The same amount of 
light is claimed to be reflected regardless of the viewing angle com- 
monly prevailing in the average theater. 144 

Comparatively few patents were issued disclosing improvements 
in screens. 148 

Theater and Stage Illumination. Shook 146 has described an instru- 
ment for the projection of "mobile color," which utilizes a single 
light source and three rotating disks on which are placed various 
optical devices and light filters. An instrument called the "Muto- 
chrome" has been designed by Smith for projection of scenic back- 
grounds or color schemes for the design of decorative materials. It 
consists of a number of similar optical systems together with prisms 
for obtaining light from a common source. 147 

Theater Acoustics and Construction. Since the advent of the 
sound motion picture, more and more attention has been given to 
the question of the size and shape of auditoriums. Physical re- 
quirements, such as plot, building restrictions, etc., influence the 
choice. Any set formula is usually of little value but from experience 
to date it would appear that the most satisfactory results from the 
standpoint of sound reproduction are obtained in theaters having 

July, 1931] PROGRESS REPORT 95 

a maximum seating capacity of not over 2000 seats. In theaters 
of much larger seating capacity, the sound quality suffers con- 
siderably when the auditorium is only partially filled, whereas in 
the smaller theaters this condition is not as serious. 

A chain of midget motion picture houses is being planned for 
operation throughout the United States. The seating capacity 
will average about 200 and the shows will vary in duration from !."> 
minutes to 1 hour, as it is considered that some theater-goers desire 
only a short period of entertainment in their spare time. 148 

In connection with the statement that about 55 per cent of the 
22,731 theaters in the United States are now wired for sound, it is 
of interest to learn that the Opera of Malta, which has remained prac- 
tically unchanged since it was built 200 years ago, has recently been 
wired for the showing of sound pictures. 149 In an open air theater 
in Shanghai, China, the projector is enclosed in a cement booth and 
the sound screen has been placed before the back of the stage erected 
for dramatic performances. The theater seats 3000 persons and 
dialog can be heard clearly 400 feet back from the screen. 160 

Schlenker 151 has published a description of a portable laboratory 
for diagnosing theater acoustics. Results of a number of tests are 
included. A new type of electrical reverberation meter especially 
adapted to field work was described by Hopper 152 at a meeting of 
the Acoustical Society of America in December, 1930, at which time 
papers were also presented on several allied subjects. Hopper's 
apparatus consists essentially of a condenser microphone amplifier 
having a variable gain control, detector, relay, and cycle counter. 
An acoustimeter has been described which was designed especially 
for measuring reverberation times for auditoriums as well as noise 
levels existing in sound stages. 153 

According to a U. S. Government Bureau report, acoustic problems 
in Brazilian theaters are very difficult to solve. Walls are made of 
concrete or stucco and seats of plain wood. It is extremely difficult 
to use drapes as the insects attack most materials used. Electric 
current is quite unsatisfactory in many cities for sound installations. 
There is also a scarcity of skilled projectionists. 15 


A . Education, Business, and Legal Records 

Production of sound pictures has been initiated by the U. 

Department of Agriculture in its own studio in Washington. One 


of the first pictures scheduled is the Indian sign language film which 
is being made for the U. S. Department of the Interior. 155 Officers 
of the U. S. Army are to be trained in the technic of sound motion 
picture production according to the announcement of the Bulletin 
of the Academy of Motion Picture Arts and Sciences. 1 

According to Baer 167 concrete experiences are a necessary pre- 
requisite to the use of language, and visual aids, properly used, 
equip a group with a common body of life experiences. The various 
phases of the application of motion pictures as visual aids are stressed. 
Over three million dollars were spent for visual instruction in the 
14 largest cities of the United States from 1923 to 1930. 158 In the 
Days of Chivalry, a school film edited from the feature picture, Robin 
Hood, was shown successfully in 20 public schools. It represented 
the first attempt to prepare an entire school film from a feature 
picture. 159 

Sound pictures are receiving attention in England. A regular 
series of educational newsreels is being prepared for British school 
and college distribution, using portable sound equipment if neces- 
sary. 160 Four one-reel sound pictures were shown on February 2nd 
in a West London school and questionnaires were distributed for 
teachers who will report on the relative merits of sound vs. silent 
pictures. 161 In December, 800 educational associations were called 
into conference at Burlington House to consider the value of motion 
pictures as a medium of education. 162 

In Finland, two associations doing educational work are using 
amateur standard film. 163 

Mogenson 164 recommends the use of motion picture films for the 
instruction of time study workers. 

B. Medical Films, Radiography, and Cine Photomicrography 

At the Fall, 1930, Meeting of the Society, Morrison 165 described 
a laryngoscope for making full-screen pictures of the vocal cords at 
the rate of 16 frames per second. According to Schmidt, the Ham- 
burg Film Archive, which specializes in medicosurgical subjects, 
was organized to supply such films at low cost to universities. 166 

The difficulties facing the designer of equipment for x-ray cinema- 
tography are reviewed by Roswell. 167 

Lucas 168 described and demonstrated his ultra-violet microscope 
at the New York meeting of the Society in 1930. Its applications 
to the study of biological and medical specimens were reviewed. 

July, 1931] 



No cutting or staining of specimens is required when taking photo- 
graphs of various sectional planes of the specimen. 

C. Television 

At a test made on February 12th, in the General Electric Labora- 
tories, the features of a professor of the University of Leipsig, Ger- 

FIG. 6. Multiplex television projector. 

(Reproduced by courtesy Electronics, N. Y., and Gramophone Co., Ltd., 

Hayes, England.) 

many, were recognized by his friends as televised across the Atlantic 
ocean from Schenectady. According to the same article, progress 


has been reported in the making of motion pictures of televised 
images. 169 About 1000 television sets are reported to be in use in 
the United States. 170 

Jenkins 171 has suggested a scanning screen for television composed 
of a plurality of cells, each actuated by its own shutter, composed 
of aluminum foil and controlled electrostatically by means of a 
synchronous commutator. 

A motion picture film was used by Sanabria at Chicago in demon- 
strating the projection of a televised image on a screen 10 feet 
square. 172 

Ives has made further progress with his television experiments 
and has found that scanning by purple light gives better repro- 
duction of image tones. Potassium photo-cells sensitive to the blue 
component of the purple light were used in conjunction with caesium 
cells for the red. 173 Ives has also constructed a three-channel system 
in which prisms, placed over the holes in a scanning disk, direct 
the incident light into three photoelectric cells. The three sets 
of signals are transmitted over three channels to a triple electrode 
neon lamp placed behind a viewing disk also provided with prisms 
over its apertures. An image of 13,000 elements is thus produced. 174 
Good telephotographs contain about 250,000 elements, however, 
and according to Gannett 175 it is quite impractical under present 
conditions to radio-broadcast such pictures as it would require a 
frequency band 4 million cycles wide, the equivalent to 400 ordinary 
broadcast channels. Such a band would mean nearly complete 
monopoly of present transmitting channels. 

A new multiplex system of television was introduced in England 
recently which uses a standard motion picture projector for trans- 
mission of pictures (Fig. 6). Five transmission channels are em- 
ployed, each transmitting one-fifth of the picture. Much more 
light is therefore claimed to be available to illuminate the receiver 
screen, which may be full size. 176 

Two patents dealing with television methods were noted. 177 

D. General Recording and Miscellaneous Uses 

An apparatus has been devised by Withrow and Boyd 178 which 
makes possible simultaneous flame and pressure studies by photog- 
raphy of individual explosions in a gasoline engine. The results 
indicate that the phenomenon of knock in the engine is due to a 
many-fold increase in the rate of inflammation within the latter 

July, 1931] PROGRESS REPORT 99 

portion of the charge. The flame pictures were made on a constantly 
moving film through a quartz window in the cylinder head. 

Winzenberg 179 has described a new camera of German design, 
capable of speeds up to 1500 exposures per second. The path of 
flight of a moving body such as an airplane may be determined 
accurately by use of a theodolite camera using motion picture film. 180 
Slow motion pictures of the flight of trained eagles and falcons are 
being used in Germany to train glider pilots. 181 

Positions of the body during sleep have been recorded with a 
motion picture camera in an investigation conducted at the Mellon 
Institute. The camera is placed on a shelf near the bed and is 
actuated by a magnetic circuit breaker attached to the bed springs. 
A second exposure is made automatically one minute after the first 
by means of a supplementary mechanism. 182 

Only three patents were noted covering development in methods 
of general recording. 183 


Comparatively few color motion pictures were released during 
the past six months. Nevertheless, laboratories equipped for color 
work continued to improve their processing equipment and devise 
additional refinements in their processes. With the marked im- 
provement in the speed and color-sensitivity of panchromatic emul- 
sions, coupled with improvements in optical systems, lighting equip- 
ment, and processing, it is likely that further refinements will be 
forthcoming in color print quality. 

Clark 184 has prepared a list of 32 color processes which have been 
enjoying more or less commercial exploitation during the past year. 
The list is stated to be incomplete but some evidence of the interest 
being shown in color processes may be gained from an examination 
of it. Although it is evident from an inspection of the list that sub- 
tractive processes, requiring no change in projection equipment, have 
been the most popular, it is significant that a well-known producing 
organization demonstrated a three-color additive process at the 
meeting of the New York Section of the Society in December, 1930. 
Both originals and prints made by this process (Keller- Dorian) were 
shown. The film has horizontally embossed lenticulations and the 
copies were said to have been made by a new optical printing 
process. 185 

In order to reduce extra noise accompanying the running of a 

100 PROGRESS REPORT [J. S. M. p. E. 

sound color camera, Benson 186 has suggested that the camera be en- 
closed in an evacuated housing mounted on a resilient pad. 

Macrae 187 offers the suggestion that the screen should be farther 
from the front seats for an all -color program than for an ordinary 
program. The extent of the "color field" is less than for a normal 
field of view since the sensitivity of the eye for color diminishes 
toward the periphery of the field of vision. 

A general review of the processes of color photography was pre- 
sented by Matthews 188 before the Fall, 1930, Meeting of the Society. 

A limited number of patents were issued dealing with cameras 
and projectors for three-color additive processes. 189 

Four patents were noted disclosing methods of manufacturing 
multicolor screen films. 190 Lenticular screen processes were pro- 
tected by two patents. 191 Three patents were issued covering two- 
color additive processes for cinematography. 192 

Brewster and Miller 193 have advanced suggestions based on experi- 
mental research regarding the most promising process for making 
three-color subtractive motion pictures. 

Another application of the bi-pack method of exposure has been 
made in the Magnacolor process. 194 Two emulsions are used face 
to face. The front emulsion is blue-sensitive and is coated with 
a red dye on its surface. The back emulsion is panchromatic. 
Exposure is made through the support of the red dyed film. Details 
of processing, which are said to be worked out under patent pro- 
tection, include exact registration in printing, application of the dyes 
in processing the positive, and machinery for developing and printing. 

A historical resume of the Kodachrome process has been published 
by Matthews, 195 showing that the first observations on the principles 
underlying this two-color process were made in 1910 by Capstaff. 

As noted earlier in this report, the first industrial motion picture 
made by the Multicolor process was produced during the past six 
months under the title Stepping Ahead. A short account of a two- 
color subtractive process for animated cartoons with sound was 
published by Pander. The process was brought out by the Ufa 
Company in Germany. 196 

The Pilney system of color cinematography makes use of two 
laterally inverted images photographed side by side on a double 
width film which is folded down its length for projection purposes. 
vSpecial double coated positive stock is used but technical details 
have not been published. 197 

July, 1931] PROGRESS REPORT 101 

Patent protection was granted on a limited number of processes 
for making motion pictures by subtractive methods. 198 


A . General Equipment and Uses 

In a paper presented at the New York convention in October, 
1930, Holslag 199 reviewed the status of home sound movies and 
concluded that only a modest distribution of sound equipment will 
be realized. Widespread use of such equipment is more likely to 
be found among a new group of users who are interested in it as an 
entertainment source rather than as a hobby. 

Amateur Cameras. Although amateur cinematography continued 
to enjoy increasing patronage during the past half year, there were 
comparatively few new pieces of equipment added to the present 
comprehensive list. In April, a new camera was announced which 
was claimed by its manufacturers to be the lightest camera using 
16 mm. film yet offered to the market. When loaded with 100 feet 
of film, it weighs 3 x /2 pounds and is 8 3 /4 in. high by 5 in. wide by 
about 2 in. thick. The frame is made of duralumin throughout. 200 

According to an announcement in a British publication, 201 a 
new combined camera and projector for amateur use has been 
developed. A row of pictures is exposed across a film, 4V 2 inches 
wide. The film then moves upward to make room for another row 
in the reverse direction. A special reflector in the projector permits 
use of a smaller wattage bulb than is normally required in amateur 

A few patents have been issued on amateur cameras. 205 

Projectors. In spite of many reports that 16 mm. projectors, 
which may be used with sound-on-film records, are available for 
the market, 203 none have actually appeared. It is believed, how- 
ever, that much progress has been made in this field and such equip- 
ment will doubtless be offered in the near future. 

Additional types of equipment for use with disk records continued 
to be made available. In one type supplied by the Pacent Electric 
Company, the cabinet has been designed to hold both the turntable 
and projector. The amplifier is housed in a separate cabinet which 
also contains a loud-speaker unit. 204 Bell & Howell have announced 
a portable home movie equipment comprising a projector with a 
synchronized turntable, and also a radio set, 206 in the same cabinet. 

A sound projector called the Animatophone is so designed that 

102 PROGRESS REPORT [J. S. M. p. E. 

the sound disk record rotates in a vertical plane and is connected 
directly to the projector motor shaft. Two speeds of rotation are 
possible, each maintained constant by a governor. 206 In the Ampro 
projector for 16 mm. film described by Shapiro, 207 two features 
are emphasized, viz., a high speed intermittent and cylindrical 
shutter giving 64 interruptions per second, and the use of a 20-volt 
lamp which permits high screen illumination. 

The Lytax projector uses a 250-watt, 50-volt lamp and is designed 
to take 16 mm. film. 208 

Several inexpensive projectors such as the Kodatoy, the Movector, 
etc., have been marketed, intended primarily as toys for children. 

Projectors and projection accessories were protected by several 
patents. 209 

Accessories. The demand for more light for the projection of 
amateur films has been answered by the introduction of several 
improved types of lamps. At the New York meeting of the Society 
last October, Roper and Wood 210 reported the results of illumination 
measurements on lamps of low voltage. The advantages of the 
20-volt lamp are obvious, both for spherical and aspheric condenser 
systems, a gain of 25 per cent in screen illumination being shown 
over 50-volt lamps of the same wattage. More recently, a 375-watt, 
75- volt lamp was made available, which is still a greater improve- 
ment over the previously used types. 211 

Two recorders for making records to be used in conjunction with 
amateur projectors have been made available on the English market. 
The Kingston can be used only for direct acoustic recording but the 
Cairmor may be used for either acoustic or electrical recording of 
6, 8, or 10 in. records. 212 

A special microphone used with the Filmophone projector enables 
the operator to make running comments through the loud speaker 
while the film is being shown. A synchronized disk is used which 
may be disconnected while the microphone is being used. 213 

Only a limited number of patents were issued noting improvements 
in 16 mm. accessories. 214 

Films and Film Processing. Working instructions for the reversal 
of 16 mm. cin film have been published by Gibbs. 216 At the Con- 
gress of German Broadcasters held in Vienna last fall, sound records 
on paper were shown for playing in conjunction with amateur 
cinema projection. 216 The sound is recorded on sensitized paper 
strips, 6 mm. wide, on which there is room for four sound tracks. 

July, 1931] PROGRESS REPORT 103 

Three hundred meters require 40 minutes for reproduction. The 
record is of the variable width type and may be printed either photo- 
graphically or mechanically on paper. Sound is reproduced by 
light reflected from the paper. 

Three patents were noted which were related to 16 mm. film 
processing. 217 One patent was issued on a method of titling films. 218 

B. Amateur Color Processes 

Apparatus for photographing growing plants in their natural 
colors has been described by Ricker. 219 Kodacolor film was used. 
For stop motion pictures, the camera and lights are controlled auto- 
matically by means of a timed contact disk, which, through a relay, 
operates a master switch that turns on the light and starts the camera. 

One patent has been issued for making component color records 
on film narrower than 35 mm. intended for additive synthesis 220 
and three patents were noted covering processes using lenticulated 
films. 221 


There are a total of 75 theaters in the U. S. Army camps and posts 
in the United States, of which 58 were equipped for sound pictures 
during 1930. About 17,000 performances are given yearly and the 
average house seats 400 persons. 222 According to data supplied 
by the Motion Picture Division of the U. S. Department of Com- 
merce, there are a total of 62,365 theaters in the world, as of De- 
cember, 1930, of which 19,894 had been equipped for sound picture 
projection. A later bulletin from the Bureau reported that there 
are approximately 7720 theaters wired for sound in Europe exclusive 
of Soviet Russia. There were 1320 theaters equipped during the 
last three months of 1930. 223 

Europe now has 33,870 motion picture theaters, representing an 
increase of 11,445 houses since 1926, seating 5,283,000 persons. 114 
North and Golden 225 reported at the Fall, 1930, Meeting of the Society 
on equipment, installations, and general conditions existing in the 
industry abroad. At this meeting, Irby 226 gave an excellent sum- 
mary of the patent situation, past and present, here and abroad. 

A preliminary survey made by the Motion Picture Division of 
the U. S. Department of Commerce indicated that there were over 
2000 concerns in the United States using motion pictures for business 
purposes. Further effort is being made by the Bureau to help 


formulate plans for the most effective use of films, as well as to in- 
crease the distribution of available films. 227 

Cameramen in the East were paid over $800,000 for their services 
during 1930. Studio cameramen received $161,980, and $26,543 
for overtime work. 228 

Film exports fell off slightly for the year 1930, as reported by 
Golden, 229 compared with 1929, although the actual valuation 
increased. Footage and valuation were as follows: 

1930274,351,000 linear feet valued at $8,118,000 
1929282,215,000 linear feet valued at $7,622,000 

Of the total footage exported, 186,436,000 feet or 67 per cent 
represented sound pictures. There were 261,995,000 feet of positive 
film and 12,355,000 feet of negative film exported during 1930, 
compared with 273,772,000 feet of positive and 8,443,000 feet of 
negative during 1929 (an abnormal year due to the introduction of 
sound film). Of the total negative footage exported, 8,190,000 or 
about 61 per cent constituted sound films. From the figures given 
for negative film exports, it is seen that there was an increase for 
1930 over 1929 of about 50 per cent. Golden considers that this in- 
dicates that more positive film is being printed abroad than in pre- 
vious years. 

Domestic sound picture equipment sales for 1930 totalled $32,635,- 
000 according to Electronics and export sales amounted to $8,250,- 
000, which made the total equipment sales equal $40,885,000. This 
same authority estimated that $192,000,000 was paid out by the 
motion picture industry during 1930 compared with $180,864,000 in 

Under the five-year plan of the Soviet Union, it is expected that 
there will be approximately 52,000 theaters established by October, 
1933. This will include 24,000 regular cinemas, 19,000 school 
theaters in Russia proper, and 9000 in the Ukraine. 231 Up to 
April, 1931, 296 Italian theaters had been equipped with sound 
film reproduction apparatus. 232 

A member of this committee, residing in Bombay, reported that 
there had been 14 new sound installations made in Indian theaters 
since the previous report, so that there are now 42 theaters equipped 
for sound pictures. Three companies are producing sound pictures, 
chiefly short subjects. A ten-reel sound picture feature was com- 
pleted by the Imperial Film Company, Bombay, for release in 

July, 1931] PROGRESS REPORT 105 

March, 1931. Sound pictures are reported to be very popular 
among Indian audiences. 

Australia has 641 theaters wired for sound, of which 136 houses 
are equipped for disk reproduction only. As an indication of the 
rapid progress made in recent months, it is estimated that 95 per cent 
of the equipment was contracted for during the past year. 233 


A significant business transaction relative to trade publications 
in the United States occurred late in the year 1930 when the Quigley 
Publishing Company took over the publication of Exhibitors Herald- 
World and Exhibitors Daily Review and Motion Pictures Today. 
These two journals were discontinued as well as Motion Picture 
News (published for many years by the Quigley Publishing Co.), 
and beginning January 1, 1931, the following new journals were 
started: Motion Picture Herald (weekly), and Motion Picture 
Daily. The first number of a new French technical journal devoted 
to the motion picture industry appeared in October, 1930, under the 
name La Technique Cinematographique. 

New books which have appeared are as follows: 

1. Kinemato graph Yearbook 1931, Kinematograph Publications, Ltd., Lon- 

2. The British Journal Photographic Almanac, 1931, Greenwood & Co., Ltd., 

3. Soviet Photo Almanac, edited by Soviet Photo, Ogonyok, Ltd., Moscow. 

4. General Annual of Cinematography (Annuaire General de la Cinematog- 
raphic 1930-1931), Cine Magazine, Paris. 

5. Publications from the Scientific Laboratory, Agfa, Photographic Division 
(Veroffentlichungen des wissenschaftlichen Zentral Laboratoriums Agfa: Photo- 
graphischen Abteilung), by I. G. Farbenindustrie Aktiengesellschaft, S. Hirzel, 

6. Photogrammetry and Aerial Surveying (Photogrammetrie und Luftbild- 
wesen), by R. Hugershoff, J. Springer, Vienna. This is Vol. VII of Handbuch 
der wissenschaftlichen und angewandten Photographic, edited by A. Hay. 

7. The Manufacture of Photographic Plates, Films, and Papers (Der Fabrika- 
tion des Photographischen Flatten , Filme, und Papier e), by J. M. Eder and F. 
Wentzel; The Use of Photographic Plates, Films, and Papers (Der Verarbeitungen 
der Photographischen Flatten, Filme, und Papiere), by J. M. Eder, Luppo-Cramer, 
M. Andresen and A. Tanzen. These are Vol. 3, Pts. 1 and 2, respectively, of the 
6th Edition of Ausfuhrliches Handbuch der Photographic. W. Knapp, Halle. 

8. Photography Its Principles and Practice, by C. B. Neblette, Van Nos- 
trand, New York, 2nd Edition. 

9. The Talkies, by A. E. Krows, H. Holt & Co., New York, N. Y. 
10. The Talkies, by Crosley Lockwood and Son, London. 

106 PROGRESS REPORT [J. S. M. p. E. 

11. Sound, by E. G. Richardson, Arnold & Co., London. 

12. Panchromatic Photography, Photo- Miniature No. 203, edited by J. A. 
Tennant, Tennant & Ward, New York, N. Y. 

13. Basic Photography, U. S. Air Corps Training Normal, War Department, 
Washington, D. C. 

14. The. Construction and Equipment of Chemical Laboratories, edited by the 
National Research Council, Chemical Foundation, Inc., New York. 

15. Theory and Practice of Hyper sensitizing (Der Theorie .und Praxis der 
Hypersensibilisierung) , by K. Jacobsohn, Union Deutsche Verlags., Berlin. 

16. Photographic Cells and Their Applications, by J. S. Anderson, editor, 
Phys. & Opt. Soc., London. 

17. Sound Pictures: Principles and Practice of Their Production and Exhibi- 
tion (Der Tonfilm: Grundlagen und Praxis seiner Aufnahme und Wiedergabe), 
Vol. 4, H. Umbehr, editor Verlag der Lichtbildbiihne, Berlin. 

18. Acoustics, by G. W. Stewart and R. B. Lindsay, Van Nostrand Co., 
New York, N. Y. 

19. The Practice of Color Photography (Der Praxis der Farbenphotographie), 
by E. Konig and K. Jacobsohn, Union Deutsche Verlags, Berlin. 

20. Color Photography, by F. R. Newens, Blackie & Son, London. 

21. Visual Aids in Education, by J. J. Weber, Valparaiso University, Val- 
paraiso, Ind. 

22. Fundamentals of Television, by T. W. Benson, Mancall Publishing Corp., 
New York, N. Y. 

23. George Eastman, by C. W. Ackermann, Houghton, Mifflin Co., New York, 
N. Y. 


1 Mot. Pict. Daily, 29 (Jan. 3, 1931), p. 1. 

2 Amer. Cinemat., 11 (Oct., 1930), p. 9. 

3 Amer. Cinemat., 11 (Mar., 1931), p. 9. 

4 Amer. Cinemat., 11 (Apr., 1931), p. 17. 

5 U. S. Pats. 1,765,944; 1,769,518; 1,787,824; 1,787,825; Brit. Pat. 328,874; 
Fr.Pats. 676,931; 680,942; Ger. Pat. 502,854. 

6 Kinemat. Weekly, 166 (Dec. 18, 1930), p. 15. 

7 Amer. Cinemat., 11 (Mar., 1931), p. 20. 

8 Brit. J. Phot., Color Supp., 24 (July 4, 1930), p. 26. 

9 /. Soc. Mot. Pict. Eng., 16 (Feb., 1931), p. 179. 

10 Rochester Sunday American, 9, Sect. M (Nov. 23, 1930), p. 1. 

11 /. Soc. Mot. Pict. Eng., 15 (Oct., 1930), p. 509; Amer. Cinemat., 11 (Dec., 
1930), p. 9. 

12 Amer. Cinemat., 11 (Nov., 1930), p. 10. 

13 /. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 286. 

14 Kinotechnik, 12 (Nov. 20, 1930), p. 566. 

16 U. S. Pats. 1,767,849; 1,770,351; 1,773,575; Ger. Pats. 493,994; 495,842; 
Brit. Pat. 332,906; Fr. Pat. 682,999. 

16 Internal. Phot., 2 (Dec., 1930), p. 43. 

17 Amer. Cinemat., 11 (Dec., 1930), p. 11. 

18 Internal. Phot., 3 (May, 1931), p. 36. 

July, 1931] PROGRESS REPORT 107 

19 Filmtechnik, 6 (Nov. 15, 1930), p. 5. 

2 U. S. Pats. 1,764,407; 1,765,904; 1,767,846; 1,767,847; 1,767,848; 1,770,659; 
1,772,772; 1,772,774; 1,773,594; 1,777,419; 1,777,682; 1,779,653; 1,780,384; 
1,783,463; 1,786,917; 1,787,271; 1,789,222; 1,789,289; Fr. Pats. 669,963; 671,894; 
671,931 ; 673,454; 674,097; 677,788; 677,864; 678,952; 681,041 ; Brit. Pats. 328,784; 
329,254; 330,248; 330,267; 336,110; 337,143; 337,961; Ger. Pats. 496,010; 500,870; 
500,873; 504,752; 505,655. 

21 U. S. Pats. 1,783,399; 1,784,515; 1,785,336; Fr. Pats. 676,972; 682,612; 
Ger. Pats. 493,643; 495,685; Brit. Pat. 339,368. 

22 U. S. Pats. 1,762,378; 1,768,772; Fr. Pat. 679,724. 

23 Brit. Pat. 333,750; U. S. Pat. 1,778,351; Ger. Pat. 504,853. 

24 Kinotechnik, 12 (Nov. 20, 1930), p. 595. 

25 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 710. 

26 J. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 689. 

27 Kinotechnik, 12 (Sept. 5, 1930), p. 484; also Filmtechnik, 6 (Oct. 18, 1930), 
p. 13. 

28 Trade Report, Mot. Pict. Div. U. S. Dept. of Commerce, March 4, 1931. 

29 U. S. Pat. 1,767,668. 

30 Theater Management, 25 (July, 1930), p. 11. 

31 Brit. Pat. 332,898; Ger. Pat. 504,615. 

32 U. S. Pat. 1,788,740. 

33 Mot. Pict. Herald, 102, Sect. 1 (Jan. 10, 1931), p. 35. 

34 Kinotechnik, 12 (Sept. 20, Oct. 5, 1930), pp. 499 and 525. 

35 Electronics, 2 (Mar., 1931), p. 542. 

36 Ex. Herald-World, 101 (Dec. 27, 1930), p. 30. 

37 Mot. Pict. Herald, 102, Sect. 2 (Mar. 14, 1931), p. 74. 

38 Mot. Pict. Herald, 102 (Jan. 24, 1931), p. 42. 

39 J. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 23. 

40 J. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 3. 

41 J. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 653. 

42 J. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 602. 

43 Kinotechnik, 12 (Sept. 5, 1930), p. 468. 

44 Filmtechnik, 6 (Sept. 20, 1930), p. 10. 

45 Electronics, 2 (Feb., 1931), p. 512. 

46 Ann. Physik, 4 (Sept., 1930), p. 1017. 

47 Ann. Physik, 4 (Sept., 1930), p. 1058. 

48 Projection Eng., 3 (Jan., 1931), p. 19. 

49 Filmtechnik, 6 (Oct. 18, 1930), p. 21. 

50 /. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 269. 

51 J. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 315. 
62 Amer. Cinemat., 11 (Sept., 1930), p. 15. 

83 Filmtechnik, 6 (Nov. 15, 1930), p. 20. 

84 /. Soc. Mot. Pict. Eng., 16 (Apr., 1931), p. 399. 

88 U S Pats 1 758,794; 1,758,832; 1,759,434; 1,759,580; 1,759,581; 1,761,61 
1,765,997; 1,767,547; 1,768,403; 1,769,907; 1,769,908; 1,771,992; 1,771,925; 
1,776,969; 1,777,418; 1,777,828; 1,778,104; 1,781,945; 1,781,550; 1,780,68 
1,786,025; 1,786,368; 1,786,274; Brit. Pats. 328,299; 329,098; 331,785; 331,85 
333,154; 334,353; 334,354; 334,576; 335,882; 336,559; 336,699; 336,981; 337,26 


::iO; 337,783; 337,954; 338,847; 339,073; Fr. Pats. 670,231; 671,097; 674,912; 
676,054; 676,391; 678,215; 678,631; 678,783; 681,692; 681,733; 682,384. 
Ex. Herald-World, 100, Sect. 1 (Aug. 23, 1930), p. 47. 
' Kinotfchnik, 12 (Aug. 20, 1930), p. 435. 
/. Soc. Mot. Pict. Eng., 16 (Feb., 1931), p. 159. 
" J. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 330. 
U. S. Pat. 1,785,631; Fr. Pat. 670,291. 
/. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 627. 
Zeit. wiss. Phot., 27, No. 8/9 (1930), p. 236. 
61 Camera (Luzern), 9 (Nov., Dec., 1930), pp. 128 and 164. 
/. Soc. Mot. Pict. Eng., 16 (April, 1931), p. 437. 

Kinotechnik, 12 (Oct. 20, 1930), p. 549; ibid., 12 (Nov. 5, 1930), p. 574. 
** Kinemat. Weekly, Supp. 170 (Apr. 16, 1931), p. 25. 
Bull. Acad. Mot. Pict. Arts & Sci. (Mar. 5, 1931), p. 10. 
67 Electronics, 2 (Jan., 1931), p. 464. 
Technique Cinemat., 1 (Nov.-Dec., 1930), p. 8. 
U. S. Pat. 1,762,925. 

70 /. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 38. 

71 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 671. 

72 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 587. 

73 Filmtechnik, 7 (Jan. 10, 1931), p. 7. 

74 Kinemat. Weekly, 166 (Dec. 11, 1930), p. 61. 

75 U. S. Pats. 1,764,938; 1,771,029; 1,776,330; 1,779,947; 1,783,045; 1,788,308; 
1,789,112; Brit. Pats. 328,423; 303,024; 333,634; 334,359; 337,742; 339,302; 
Fr. Pats. 673,178; 675,123; 678,698; 680,818. 

76 J. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 57. 

77 U. S. Pat. 1,772,622. 

78 Kinemat. Weekly, 162 (Aug. 14, 1930), p. 69. 

79 Internal. Phot., 3 (Mar., 1931), p. 13. 

80 U. S. Pats. 1,776,049; 1,776,058; 1,780,510; 1,785,215; Brit. Pats. 329,785; 
331,122; 331,123; 335,780; Fr. Pats. 674,727; 678,459; 681,805. 

81 U. S. Pats. 1,765,998; 1,778,495; Fr. Pats. 677,628; 679,736. 

82 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 676. 

83 U. S. Pat. 1,768,895; Fr. Pats. 677,629; 680,583; Ger. Pat. 505,841. 

84 Annual Report, 1930, Acad. Mot. Pict. Arts & Sciences, p. 20. 

86 Bull. T-45, Mot. Pict. Div. U. S. Dept. Com., Mar. 25, 1931, p. 2. 

88 Electronics, 2 (Feb., 1931), p. 502; also Wall St. J. (March 18, 1931), p. 7. 

87 Mot. Pict. Monthly, 6 (Dec., 1930), p. 2. 

88 Ex. Daily Rev. & Mot. Pict. Today, 28 (Oct. 4, 1930), p. 14. 
"Kinotechnik, 12 (Sept. 20, 1930), p. 512; ibid., 13 (Mar. 1, 1931), p. 95. 

90 Kinemat. Weekly, Supp. 164 (Oct. 9, 1930), p. 41. 

91 Cineopse, 12 (Nov., 1930), p. 438. 

92 U. S. Pats. 1,764,201; 1,771,591; 1,771,748; 1,772,782; 1,774,298; 1,776,109; 
1,776,110; 1,778,635; 1,780,945; 1,783,340; 1,784,097; 1,784,138; Brit. Pats. 
328,785; 329,617; 329,662; 330,329; 331,012; 334,095; 334,532; 335,075; 335,226; 
335,534; 335,891; 336,197; 339,644; Ger. Pats. 493,759; 497,667; 501,043; 501,044; 
505,741; Fr. Pats. 674,822; 678,348; 678,361. 

98 Kinemat. Weekly, 164 (Oct. 23, 1930), p. 45. 

July, 1931] PROGRESS REPORT 109 

94 Ex. Herald-World, 100, Sect. 2 (Aug. 2, 1930), p. 34. 

95 Film Daily, 55 (Feb. 20, 1931), p. 1; also /. Soc. Mot. Pict. Eng , 16 (Feb 
1931), p. 131. 

96 Kinemat. Weekly, 165 (Nov. 20, 1930), p. 65; also Bioscope (Mod. Cinema 
Technique}, 85 (Oct. 1, 1930), p. v. 

97 Kinemat. Weekly, Supp. 164 (Oct. 9, 1930), p. 50. 

98 Bioscope (Mod. Cinema Technique), 86 (Jan. 7, 1931), p. iii. 

99 Filmtechnik, 6 (Nov. 15, 1930), p. 14; also Kinotechnik, 12 (Sept. 20, 1930) 
p. 506. 

100 Filmtechnik, 6 (Dec. 13, 1930), p. 6. 

101 J. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 349. 

102 Ex. Daily Rev. fir Mot. Pict. Today, 28 (Dec. 13, 1930), p. 13. 

103 /. Soc. Mot. Pict. Eng., 16 (Feb., 1931), p. 144 

104 Mot. Pict. News, 42 (Aug. 23, 1930), p. 32. 

105 Kinotechnik, 13 (Mar. 1, 1931), p. 95. 

106 Electronics, 1 (Oct., 1930), p. 333. 

107 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 610. 

108 Filmtechnik, 6 (Sept. 20, 1930), p. 10. 

109 Zeit.fur Tech. Phys., 12 (Feb., 1931), p. 116. 

110 Electronics, 2 (Feb., 1931), p. 512. 

111 Intern. Rev. Educational Cinemat., 2 (Oct., 1930), p. 1191. 

112 Kinotechnik, 12 (Oct. 5, 1930), p. 528; ibid., 13 (Feb. 5, 1931), p. 52. 

113 Kinotechnik, 13 (Jan. 20, 1931), p. 33. 

114 Phot. Ind., 29 (Feb. 27, 1931), p. 237. 

115 Kinotechnik, 13 (Mar. 1, 1931), p. 84. 

116 /. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 341. 

117 U. S. Pats. 1,768,063; 1,774,253; 1,777,037; 1,778,084; 1,786,026; 1.78*',, 
1,786,903; Brit. Pats. 329,677; 330,504; 331,256; 334,501; 335,511; 336,036; 
336,157; 336,451; 336,573; 337,429; 337,697; 338,526; 338,652; Fr. Pats. 
679,177; 680,713; 681,656; 681,784; 682,120; 682,523; Ger. Pats. 497,945; 
500,424; 500,871; Austral. Pat. 21,970. 

118 Projection Eng., 2 (Nov., 1930), p. 26; also Mot. Pict. Herald. 103 (Apr. 4, 
1931), p. 63. 

119 Projection Eng., 3 (Feb., 1931), p. 20. 

120 Kinotechnik, 13 (Feb. 20, 1931), p. 59. 

121 Kinemat. Weekly, 167 (Feb. 5, 1931), p. 67; Bioscope, 85 (Dec. 17, 1930), 
p. 12. 

122 Kinotechnik, 12 (Sept. 5, 1930), p. 463. 

123 U. S. Pat. 1,787,426; Brit. Pats. 333,131; 335,864; Fr. Pats. 678,960; 

124 Internal. Rev. Educational Cinemat., 2 (Dec., 1930), p. 1379. 

125 Bioscope (Mod. Cinema Technique), 85 (Oct. 8, 1930), p. i. 

126 /. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 61. 

127 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 702. 

128 Kinotechnik, 13 (Jan. 5, 1931), p. 3. 

129 Fr. Pats. 678,434; 678,630; 680,826. 

130 U. S. Pats. 1,763,922; 1,766,607; 1,769,722; 1,769,771; Ger. Pats. 493,760; 
494,876; 497,179; 497,287; 499,803; 500,803; 500,872; 503,271; Fr. Pals. 675,865; 

110 PROGRESS REPORT [J. S. M. p. E. 

676,520; 676,574; 676,969; 677,221; (177,241; 679,334; 679,630; 680,992; Brit. 
Pots. 329,480; 333,255; 336,114. 

> Erpigram, 3 (Apr., 1931), p. 1. 

" U. S. Pat. 1,788,808. 

" U. S. Pats. 1,776,342; 1,781,053; 1,783,169; 1,786,977; Fr. Pats. 678,099; 

184 /. Soc. Mot. Pict. Eng., 16 (Feb., 1931), p. 168. 

l * /. Opt. Soc. Amer., 21 (Feb., 1931), p. 109; ibid., 20 (Oct. and Nov., 1930), 
pp. 585 and 597. 

l Mot. Pict. Herald, 102, Sect. 1 (Mar. 7, 1931), p. 12. 

l * U. S. Pat. 1,783,998; Fr. Pats. 670,052; 678,921; 679,108; 681,632. 

> U. S. Pats. 1,777,409; 1,780,123; 1,780,311; Fr. Pats. 673,710; 675,832; 
680,375; 682,294; Brit. Pats. 336,284; 339,070; Ger. Pat. 499,106. 

139 Electronics, 1 (Dec., 1930), p. 420. 

140 DuPont Magazine, 24 (Oct., 1930), p. 5. 

141 J. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 31. 
141 Kinemat. Weekly, 165 (Nov. 27, 1930), p. 32. 

143 Film Daily, 55 (Jan. 14, 1931), p. 2. 

144 Film Daily, 55 (Jan. 16, 1931), p. 1. 

145 U. S. Pat. 1,787,270; Fr. Pats. 670,973; 679,803; Ger. Pat. 500,569. 
148 /. Opt. Soc. Amer., 20 (June, 1930), p. 354. 

147 Brit. J. Phot., 77 (Oct. 31, 1931), p. 655. 

148 Barren's Weekly, 11 (Mar. 23, 1931), p. 4. 

149 Reports Mot. Pict. Div., U. S. Dept. Commerce (Nov. 19, 1930). 

150 Erpigram, 2 (Nov. 15, 1930), p. 4. 

141 /. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 302. 
UJ /. Acoustical Soc. Amer., 2 (Apr., 1931) p. 499. 

153 Electronics, 2 (Apr., 1931), p. 609. 

154 Bull. No. 41-T, Mot. Pict. Div. U. S. Dept. Commerce, Feb. 16, 1931. 

165 U. S. Daily, 6 (Apr. 21, 1931), p. 4. 

" Bull. Acad. Mot. Pict. Arts & Sciences (Oct. 1, 1930), p. 5; ibid. (Mar. 5, 
1931), p. 6. 

U7 /. Soc. Mot. Pict. Eng., 16 (Apr., 1931), p. 457. 

168 Ed. Screen, 9 (Sept., 1930), p. 215. 

1M Bull. Acad. Mot. Pict. Arts & Sciences (Nov. 1, 1930), p. 6. 

160 Kinemat. Weekly, 164 (Oct. 16, 1930), p. 50. 

161 New York Times, 80 (Feb. 3, 1931), p. 13. 
UI Brit. J. Phot., 77 (Dec. 5, 1930), p. 739. 

163 Internal. Rev. Educational Cinemat., 2 (Dec., 1930), p. 1403. 

164 Factory & Ind. Management, 80 (Sept., 1930), p. 511. 
186 /. Soc. Mot. Pict. Eng., 16 (Mar., 1931), p. 356. 

166 Internal. Rev. Educational Cinemat., 2 (May, 1930), p. 611. 

167 /. Soc. Mot. Pict. Eng., 15 (Dec., 1930), p. 815. 

168 /. Soc. Mot. Pict. Eng., 16 (Apr- 1931), p. 445. 
189 New York Times, 80 (Feb. 13, 1931). 

170 Variety, 100 (Nov. 19, 1930), p. 11. 

171 /. Soc. Mot. Pict. Eng., 15 (Oct., 1930), p. 445. 
"* Electronics, 2 (Apr., 1931), p. 602. 

July, 1931 ] PROGRESS REPORT 1 1 1 

173 J. Opt. Soc. Amer., 21 (Feb., 1931), p. 101. 

174 Bell System Tech. J., 10 (Jan., 1931), p. 33. 

175 Mot. Pict. Herald, 102 (Apr. 18, 1931), p. 12. 

176 Electronics, 2 (Apr., 1931), p. 593. 

177 U. S. Pat. 1,763,357; Brit. Pat. 334,967. 

178 2nd. Eng. Chem., 23 (May, 1931), p. 539. 

179 Zeit.fur Feinmechanik, 38 (Sept. 18, 1930), p. 1. 

180 Filmtechnik, 6 (Jan., 1930), p. 2. 

181 Amer. Cinemat., 11 (Apr., 1931), p. 22. 

182 Photo Era, 65 (Sept., 1930), p. 176. 

183 Brit. Pats. 329,067; 336,367; Fr. Pat. 682,485. 

184 Phot. J. (Supp.),7l (Apr., 1931), p. 22. 

185 /. Soc. Mot. Pict. Eng., 16 (Feb., 1931), p. 179. 

186 Kinemat. Weekly, 162 (Aug. 14, 1930), p. 63. 

187 Kinemat. Weekly, 162. (Aug. 7, 1930), p. 55. 

188 /. Soc. Mot. Pict. Eng., 16 (Feb., 1931), p. 188. 

189 U. S. Pat. 1,778,754; Brit. Pats. 334,708; 335,310; Ger. Pats. 494,763; 
500,265; Fr. Pats. 676,016; 679,567; 679,568. 

190 Brit. Pats. 333,865; 334,243; 334,265; 335,899. 

191 U. S. Pat. 1,777,954; Ger. Pats. 498,027; 498,480. 

192 Brit. Pat. 339,651; Ger. Pats. 495,686; 498,709. 

193 /. Soc. Mot. Pict. Eng. t 16 (Jan., 1931), p. 49. 

194 Amer. Cinemat., 11 (Mar., 1931), p. 20. 

195 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930,) p. 624. 

196 Phot. Korr., 66 (Oct., 1930), p. 271. 

197 Kinemat. Weekly, 163 (Sept. 11, 1930), p. 45. 

198 U. S. Pats. 1,775,938; 1,778,139; 1,787,808; Brit. Pats. 333,931; 333,932; 
333,933; 334,004; Fr. Pat. 683,707. 

199 /. Soc. Mot. Pict. Eng., 16 (Jan., 1931), p. 67. 

200 Radio Retailing, 13 (Apr., 1931), p. 56. 

201 Bioscope (Mod. Cinema Technique), 86 (Feb. 4, 1931), p. i. 

202 U. S. Pats. 1,762,939; 1,779,468; 1,781,937; Ger. Pats. 500,357; 505,591; 
505,592; 505,656; 505,657; Fr. Pat. 678,722. 

203 Phot. Dealer (Jan., 1931), p. 20; also Film Daily, 55 (Mar. 12, 1931), p. 12. 

204 Electronics, 2 (Mar., 1931), p. 566. 

205 Photo Era, 66 (Jan., 1931), p. 53. 

206 Internal. Phot., 2 (Dec., 1930), p. 33. 

207 /. Soc. Mot. Pict. Eng., 15 (Nov., 1930), p. 598. 

208 Phot. Ind., 28 (Oct. 22, 1930). 

209 U. S. Pat. 1,774,097; Ger. Pats. 493,646; 501,421; 503,675; 605,654; Fr. 
Pat. 679,515. 

210 /. Soc. Mot. Pict. Eng., 15 (Dec., 1930), p. 824. 

211 Mot. Pict. Projectionist, 4 (Mar., 1931), p. 29. 

212 Amat. Phot., 71 (Feb. 4, 1931), p. 107. 

213 Mot. Pict. Daily, 28 (Dec. 29, 1930), p. 4. 

214 U. S. Pats. 1,763,231; 1,784,281; Brit. Pats. 334,082; 339,585; Fr. Pals. 
678,427; 682,369; Ger. Pat. 505,969. 

215 Brit. J. Phot., 77 (Aug. 8, 1930), p. 475. 

1 1 2 PROGRESS REPORT [j. S. M. P. E. 

216 Reports, Mot. Pict. Div. U. S. Dept. Commerce (Oct. 29, 1930). 
" U. S. Pats. 1,762,936; 1,780,025; Brit. Pat. 337,472. 
518 U. S. Pat. 1,787,198. 
2 " Amer. Phot., 24 (July, 1930), p. 352. 
220 Brit. Pat. 335,432. 

> U.S.Pats. 1,762,143; 1,762,932; 1,762,933. 
222 Ex. Herald-World, 101 (Oct. 11, 1930), p. 35. 

225 Bull. No. 46-T, Mot. Pict. Div., U. S. Dept. Commerce (Mar. 24, 1931); also 
ibid. (Feb. 27, 1931). 

224 Ex. Daily Review & Mot. Pict. Today, 28 (Nov. 18, 1930), p. 1. 

225 J. Soc. Mot. Pict. Eng., 15 (Dec., 1930), p. 749. 
2 /. Soc. Mot. Pict. Eng., 15 (Dec., 1930), p. 739. 

227 Reports, Mot. Pict. Div., U. S. Dept. Commerce (Jan. 7, 1931). 

2 Film Daily, 55 (Jan. 9, 1931), p. 1. 

129 Bull. Mot. Pict. Div., U. S. Dept. Commerce (Feb. 7, 1931). 

230 Electronics, 2 (Mar., 1931), p. 538. 

131 Film Daily, 54 (Oct. 1, 1930), p. 1. 

232 Mot. Pict. Herald, 103, Sect. 2 (May 2, 1931), p. 76. 

233 Reports, Mot. Pict. Div., U. S. Dept. Commerce (Feb. 4, 1931). 



In Japan as in other countries of the world, the advent of the motion picture 
marked the beginning of the gradual decline of the legitimate theater as the 
principal source of entertainment for the masses. Motion pictures today are a 
universally popular form of entertainment for the Japanese people. 

In the course of years during which Japan has been assuming attributes of 
western civilization, the first requirements in manufactured products, which were 
demanded by the various steps of its progress in that direction, were brought 
from abroad. But Japan kept industrially abreast of its westernization, and 
with the imported article as a model, gradually supplied with home products 
each successive demand. Thus it was only in the regular course of events that 
Japan began to produce motion picture films in 1897, just two years after the 
importation of the first foreign reel. Possessing a theater old in tradition and 
highly developed artistically, it was only the mechanical features of motion 
picture production that presented problems which, however, were soon solved 
with varying degrees of success 

Today the combined capital of the motion picture producing companies in 
Japan is estimated at $125,000,000. Of this amount only $8,310,000 represents 
the capital of incorporated enterprises, and $116,690,000 approximately that of 
private concerns. 

* This material has been edited from Bulletin No. 35-T of the Motion Picture 
Division, U. S. Dept. of Commerce. It was prepared for the Division by Consul 
ral Arthur Garrels, Tokyo, Japan. 

July, 1931] PROGRESS REPORT 113 

The larger incorporated motion picture producing companies in Japan are: 

Silent Films Sound Pictures 

The Shochiku Cinematograph Co. The Mina Talkie Producing Co. 

The Nikkatsu Co. (Ltd.) The Eastphone Talkie Co. 

The Taikoku Kinema Theatrical Co. Teikine Motion Picture Co. 

The Makino Kinema Co. (a subsidiary of the Shochiku) 
The Kawai Motion Picture Co. 

The Shochiku enterprise produces about 100 feature films a year, and the 
Nikkatsu Company about 80. Production costs are given as approximately 
$2.50 per foot of film, or about $10,000 per average film. It is readily apparent 
that Japanese produced motion pictures are not of as high a standard in produc- 
tion to even the lesser American major films. 

Salaries of actors and directors are not generally known. Remuneration is on 
a monthly basis, with a small bonus payable at the completion of the picture. 
A leading actor or actress will take part in four or five pictures annually. It is 
stated that the salary of leading motion picture actors in Japan rarely exceeds 
$500 to $750 per month. 

Prominent stars appearing in what may be termed the romantic historical 
school of Japanese drama, "Kabuki," receive salaries ten times as large as those 
paid to motion picture artists. Only about 20 per cent of motion picture actors 
have been drawn from the legitimate theater. 

Police regulations have limited the length of motion picture programs in Japan. 
A standard length picture contains about 5480 meters. 

Distribution. Japanese films are produced primarily for Japanese consumption. 
The Shochiku Co. about a year ago established the World Film Distributing Co. 
and obtained a marketing agreement with a German firm to distribute Japanese 
films in Germany and 17 other European countries. Actual exporting, however. 
has not yet been undertaken. It is intended to limit films to classic and historical 
subjects. At present about 20 or 30 motion pictures are sent from Japan to 
Germany annually to be arranged for synchronized and sound display. Exported 
films have English titles. The larger Japanese passenger ships all show Japanese 
films, and about 50 pictures annually find a market in South America for Japanese 

The market for American "all-talkie," sound and synchronized motion pictures 
in Japan is not as extended as that for the silent films. When sound picture 
of various forms first made their appearance in Japan, they were accepted as a 
novelty. But owing to language difficulties the 100 per cent American talking 
pictures began to diminish in popularity. The rapid action and intense dramatic 
situation of the silent films sustained interest even where the titles were not 
intelligible. These features are necessarily slowed down in all-talking pu 
which depend largely on the dialog which is in English, and as it is not compre- 
hended by the Japanese audience, attention and interest flag. 

Types of Sound Picture Preferred in Japan. All-talking versions of foreign 
motion picture films have not been especially well revived in Japan because 
they cannot be understood properly or appreciated by Japanese audiences. 
Talking pictures were at first a novelty but audiences have since become 
of viewing a succession of scenes which, in many instances, are devoid of action 

1 1 4 PROGRESS REPORT. [J. S. M. p. E. 

and depend entirely on dialog to explain certain situations and to develop the 

It would appear, therefore, that sound pictures in synchronized form, that is, 
pictures with musical scores, sound effects, and occasional song numbers with 
sub-titles retained are more suitable for Japanese audiences, but since the present- 
day synchronized version of a picture is merdy a revision of the original 
all-talking negative, the movement of the story still remains slow, and from the 
Japanese point of view, often uninteresting. The chief objection to the use of 
sound equipment is the Japanese custom of having an interpreter. The com- 
bination of the two sounds makes it impossible for either the interpreter or the 
machine to be heard distinctly, and until this problem is solved, the future of the 
talking motion picture in Japan is dubious. 

Several foreign distributors in Kobe have recently imported further prints of 
their previously released and popular silent films because so many of the present- 
day sound films are considered unsuitable for distribution here. Several of the 
local independent Japanese distributors have recently imported a considerable 
number of Continental silent films to meet this demand for well-defined stories 
having speed and action, hoping thereby to combat the present falling off in 
theater admission. 

Japanese audiences were able to follow more readily the action of the story 
in the days of silent pictures as the tendency at that time was to eliminate sub- 
titles as much as possible and to explain the story by action rather than by words. 
In this connection the importance of the language barrier should not be forgotten. 
The success of one American sound picture was due to the fact that the picture 
was originally made as a silent film, and the synchronized musical score with 
sound effects was added at a later date, which robbed the picture of none of its 
action but helped its entertainment value. Plans are now under way to produce 
locally-made pictures with dialog, which may help audiences to become sound- 
minded, and thereby react favorably on the importation of synchronized pictures, 
while at the same time it should popularize sound pictures in the smaller towns 
and villages, whereas at present this type of entertainment is confined to the 
principal cities of the country. 

Motion Picture Theaters.- Motion picture theaters of all sizes and classes in 
Japan and its colonies in 1926 numbered 1097. In 1930 this number had in- 
creased to 1327. In 1912 there were only 170 theaters. Of the 1327 registered 
motion picture theaters 21 have sound installation, all of American make. There 
are a number of portable outfits for temporary installation. The owners of 
these ambulate among the theaters in the smaller country towns. Up to the 
present there have been produced only ten talking pictures in Japan. 

The following table shows the attendance at motion picture theaters and other 
forms of stage entertainment for the four years 1926-30, inclusive. 

Movie Halls Performances Total 

1926 117,805,000 35,929,000 153,735,000 

1927 127,184,000 37,220,000 164,404,000 

1928 140,263,000 41,016,000 181,279,000 

1929 152,439,000 40,055,000 192,494,000 


These figures have been compiled by the Police Affairs Bureau of the Ministry 
of Home Affairs. 

Briefly summarized, the position of sound pictures in Japan today is as follows: 

(1) dialog pictures in most instances are not suitable for the Japanese market; 

(2) synchronized pictures with too many song numbers, which would have a 
tendency to slow up the action of the story, are also unsuitable; (3) if practi- 
cable, the production of a separate negative for each picture produced for foreign 
audiences would be an asset, as more speed and action would be inserted into 
the picture. 



No radical changes in the production of color prints for motion 
pictures have come to the attention of this Committee. New varia- 
tions of well-known principles are being tried and used. The making 
of prints in large quantities with but little advance in cost over black- 
and-white prints appears to be the goal to seek. 

In connection with making negatives that do not require delicate 
and special cameras, it may be said that this stage of the art has 
been advanced by the use of bi-pack negatives. All the makers of 
studio cameras now adapt their cameras for this kind of work. 

Processes not previously listed include: 

Coloratura. This is the process of Pathe Exchange at Bound Brook, 
N. J. Negatives are made by the bi-pack method. Prints are made 
on double-sided film and are dye-toned on one side and metallic- 
toned on the other. The double-sided film, having two developed, sil- 
ver images is first treated on one side to make it dye-selective and 
from then on the film is totally submerged to receive both colors, the 
blue-green tone on one side and red dye on the opposite side, neither 
color going to the wrong side. The film is treated by machinery so 
that the work is completed in a single trip of the film through the 

Thomas Color. A single strip negative is used, on which the ex- 
posures are made in pairs. The projector is likewise equipped to 
project two images at once. Black-and-white prints are used and 
color filters supply the color. So far, the method as stated would 
cover the first Technicolor films. The Thomas method differs from 
Technicolor in that the pairs are in sequence whereas in the early 
Technicolor additive system the pairs were four frames apart. 

Graphy Color. Graphy Color claims to operate under the patent 
application of Luigi Cristiani, an Italian. Sheets of Cellophane or 
similar material, such as Celite, are dyed magenta, yellow, and blue- 

* Presented at the Spring, 1931, Meeting, at Hollywood, Calif. 


green and sensitized with bichromate. A sheet of each kind is printed 
by arc-light under the appropriate three-color separation negative 
until the faint positive print-out image has attained the proper den- 
sity. The sheets are then soaked in warm water and developed in 
dilute acid permanganate solution, which discharges the dyes roughly 
in inverse ratio to the exposure and produces positive images in three 
colors. The three sheets, after clearing and washing, are superim- 
posed on gelatin-coated paper and cemented together with gelatin 
solution, producing a three-color print with either a glossy or matte 

Gilmore Color. This system is said to be additive. Two images are 
taken in pairs side by side on 35 mm. film by turning the images to 
lie lengthwise on the film. A projector using color filters then turns 
and registers the two images on the screen by means of prisms. 
(U. S. Pat. 1,262,954, F. E. Ives, April 16, 1918.) 

Magnacolor. This name has been adopted for a color system 
by the Consolidated Laboratories. This concern is licensed by the 
owners of the Prizma patents and is following the system of using 
bi-packs for the negatives and double-sided film for the positives. 
One side of the double-sided film is colored blue by an iron solution 
and the opposite side is colored red by uranium. Operating under the 
Mason patent, each side is colored without danger of having the color 
solutions attack more than one side at a time by floating the film 
across the liquid coloring baths. Single-solution toning baths are 

Rotocolor. Harold Muller of New York is the inventor of a color 
process, Rotocolor, which is said to involve a shutter device attach- 
able to a standard projector and which is easily removable, permitting 
switching between black and white. (Film Daily, April 12, 1931.) 

Opticolor. The Opticolor Corporation has been formed in New 
York with the studio at Long Island operating a three-color additive 
process. No details are given as to the system used. (Motion Picture 
Herald, April 11, 1931.) 

Spectrocolor.K German Company has been formed to exploit a 
color process under the name of "Spectrocolor," an additive system. 
The company claims control of about forty patents covering the proc- 
ess. (Film Daily, March 24, 1931.) 

Multicolor In a process for producing color images, fixed i 
images are treated with a basic dye bath and then with a uranium 
toning and mordanting bath. Films having color component images 


on opposite sides are simultaneously printed in register from color 
component negatives. The printed positive is developed, fixed, and 
washed and the side bearing the images printed from the orange-red 
negative is toned blue by the application of an iron toning solution 
to that side only. The film is then passed through successive baths 
containing (1) water; (2) a basic red dye; (3) water; (4) a uranium 
toning and mordanting solution; (5) water; (6) hypo; (7) water; 
and dried. (Brit. Patent 339,323.) 


Lucas, Mobius, and Noack have patented the plan, for use with 
additive projection, of having the red and green pictures taken side 
by side and the blue picture below, whereby the red and green are 
shown twice as often as the blue during projection. (Ger. Patent 

F. Wulff and Company make three-color prints by first making a 
blue picture with blue-print paper and then, by imbibition, trans- 
ferring the yellow and magenta colors to the blue print. (Ger. Patent 

An improvement, said to be quite great in additive projection 
means for color, results from toning the prints and projecting by a 
rotating two-color disk. (Ger. Patents 499,012 and 499,013, F. Lierg 
and L. Pokorny.) 

W. Eibfelt has taken out a German patent for making a film with 
an emulsion that contains leuco bases of red, green, and yellow. The 
colorless dyes are dissolved in alcohol and added to a batch of emul- 
sion. Each color is separately mixed into one lot of emulsion. Four 
separated lots of emulsion, three with dyes and one without dye, are 
then joined into one batch. The mixed batch is then coated on the 
base in one layer as usual. 

The silver image that is exposed and developed in this emulsion is 
reduced to iodide or ferro copper which oxidizes the leuco colors and 
which are thereby mordanted. The unmordanted dyes are then 
washed from the emulsion. (Ger. Patent 400,350.) 

R. Ruth patents the idea of using screen plates or autochrome 
grain plates for motion pictures by adding a panchromatic emulsion 
to the opposite side of the film, so that pictures are made on both 
emulsions, in order to obtain a combination picture in which one pic- 
ture is a thin black-and-white and the other a very strong color picture. 
The object of this is to obviate graininess. (Ger. Patent 489,794.) 


Much activity is apparent in the field of making motion pictures in 
color by the Keller-Dorian system. Usually an engraved wheel 
pressed into contact with the celluloid in the heated condition forms 
the minute lenses on the base. 

The Eastman Kodak Co. makes fluted lenses in lines. The lines are 
produced by winding a mandrel with fine copper wire, which is electro- 
plated with copper. The inside of the wire spool is covered with 
nickel and a bearing is formed. The copper covering of small wires 
is etched away leaving a nickel drum with a perfect formation of sur- 
faces for impressing the celluloid base with fine lines. (Ger. Patent 
495,845; Fr. Patent 682,380.) 

The Eastman Kodak Co. proposes covering a Kodacolor base with 
a light absorbing filter color that is easily bleached, in order to pre- 
vent halation. (Brit. Patent 312,992.) 

Lumiere is evidently endeavoring to find an alternate way by means 
of which autochromes can more readily be produced. Silk strands 
are formed into blocks of the recurring three colors, which are impreg- 
nated with wax or paraffin. Thin sheets are cut on a microtome and 
the silk mosaic is applied to glass or film, the wax or paraffin is re- 
moved, and the interstices filled with black carbon dust. (Photo. 
Korr., No. 1, Vol. 66, 1930). 

A motion-picture film has the "film base printed with a foundation 
or matrix consisting of a half -million minute red, green, and blue- 
violet squares to every square inch of film," says the London Daily 
Mail of May 20, 1931. This film was shown to the Royal Photo- 
graghic Society. 


Regular panchromatic motion picture negative is exposed in a 
standard type of motion picture camera. The objective is made so 
that a color line-screen of two, three, or four colors in lines or in re- 
curring units may be inserted in the system. This system brings the 
images to focus on the screen-plate, and the image and lines are in 
focus at the film plane. By this means the line-screen is not in con- 
tact with the film. 

On the edge of the screen-plate is a clear line which photographs at 
each exposure of the image. This gives a definite registration mark 
for any particular picture. From this negative, positives may be 
printed by any means that also includes the registration line or mark. 

The projector is equipped with the same type of lens that is used 


in the camera. It also has a photo light arrangement to hold the 
registration line of the line-screen in the projector in registration with 
the marks on the positive. 

The producers are required to make no change in the photographing 
other than to use the lenses. The makers of sound equipment would 
be required to equip projectors with the electrical registration means 
and projecting objectives. No changes will be involved in the cost 
of making negatives and positives, and sound remains as it is 
now. (By W. V. D. KELLEY.) 


The outstanding difference between the Moreno camera and the 
present-day standard camera is that the Moreno camera entails 
continuous motion. The film passes through the camera at a uniform 
speed with no intermittent motion of the film or any moving part of 
the camera. A stationary image on each frame is obtained by dis- 
tributing the light transmitted by the photographic lens over a given 
area of constantly moving film by means of a revolving rectifying 
optical system of thin prisms traveling at a linear velocity equal to 
that of the film. This is an octagonal glass wheel with each face 
carrying a plano-convex lens element. 

The camera has a practical built-in exposure meter that is auto- 
matic in its action. The meter is located at the rear of the camera 


President Crabtree appointed Ralph M. Evans and H. W. Moyse 
as delegates representing the Society of Motion Picture Engineers to 
the Inter-Society Color Council, which meeting was reported to the 
S. M. P. E. by Mr. Evans as follows: 

On February 26, 1931, about forty men representing fourteen 
societies met in the Museum of Science and Industry in New York, 
N. Y., in response to a call for such a meeting by the Optical Society 
of America. Mr. L. A. Jones acted as chairman and Mr. M. Rea 
Paul as secretary. 

Mr. Irwin Priest of the Bureau of Standards, opening the meeting, 
spoke at some length on the need for a more definite color nomencla- 
ture and methods of specifying colors where a lengthy scientific speci- 
fication is too troublesome and expensive. To quote from the minutes 
of the meeting: 


"Following Mr. Priest's remarks a rather lengthy informal discus- 
sion was conducted in which practically everyone present took part. 
In the beginning there seemed to be a rather wide diversity of opinion 
as to the best mode of procedure to be followed in organizing an inter- 
society committee or council. As the discussion progressed, however, 
the ideas began to crystallize and finally almost complete unanimity 
of opinion was reached and the following resolutions were passed: 

"(1) Resolved: It is the sense of this meeting that an 'Inter- 
Society Color Council' be formed, composed of delegates from na- 
tional societies and associations interested in the standardization, de- 
scription, and specification of color. 

"(2) Resolved: It is the sense of this meeting that the delegates 
at this conference report back to their societies and associations the 
resolution which was adopted at this meeting, and request the several 
organizations to appoint their delegates and send notification of such 
appointments to the chairman of this meeting, who will be expected 
to call the first meeting of the Inter-Society Color Council, at which 
time the Council will form a permanent organization. 

"(3) Resolved: It is the sense of this meeting that the secretary 
be instructed to send minutes of this meeting to all delegates ap- 
pointed, and also to each society and association invited to send 
delegates but which were not represented, and extend at the same time 
to all societies and associations invited but not represented, an invita- 
tion to send delegates to the first meeting of the Inter-Society Color 

"(4) Resolved: It is the sense of this meeting that the several 
societies and associations be advised that they may appoint as many 
delegates to the Inter-Society Color Council as desired, but that each 
organization represented on the Council shall have only one vote. 

"(5) Resolved: It is the sense of this meeting that the present 
chairman be, and hereby is, authorized and empowered to call the 
first meeting of the delegates to be appointed to the Inter-Society 
Color Council, said first meeting to be called at such time and place 
as may, in his discretion and that of the secretary, seem most suit- 


1,742,543. Colored-Picture Transmission. HERBERT E. IVBS, Jan 
(Class 178-5.) Electrical transmission of colored pictures. It is proposed to pre- 
pare a set of transparent monochrome color records which are scanned \ 
source of light and transmitted as a single operation as color records to a distant 


point. After the transmission to the distant point, the records are reproduced as 
line images of the original and utilized to produce the original picture in colors. 

1,742,080. Method of Making Motion Pictures. PIERRE ARTIGUE, Jan. 7, 
1930. (Class 88-16.) Relating to the well-known glass shot art, in which it is 
proposed to stain a part of one or more of the screens with a photographically less 
actinic light filter color than the general illumination. 

1,742,943. Automatic Control for Photographic Printing Exposures. CLIFTON 
M. TUTTLE AND HERBERT E. WHITE, Jan. 7, 1930. Assigned to Eastman Kodak 
Company. (Class 95-90.5.) 

1,745,107. Animated Pictures in Relief. RAFAEL MENDOZA, Jan. 28, 1930. 
(Class 88-16.4.) A system for exhibiting animated pictures of objects in relief. 
Two differently colored images are projected onto a screen in laterally dis- 
placed relation. 

1,745,247. Manufacturing Foils, Films, Ribbons, and the Like from Viscose 
and Similar Cellulose Solutions. EMIL CZAPEK AND RICHARD WEINGAND, Jan. 
28, 1930. (Class 18-57.) 

1,746,330. Color Photography. JAMES G. ZIMMERMAN, Feb. 11, 1930. 
(Class 95-2.) A photographic printing blank having a plurality of light-sensitive 
areas presenting three colors, and in such a manner that the combination of any 
two of which colors will produce a color complementary to the third color. 

1,746,584. Apparatus for Taking Views and for the Reproduction of Cinema- 
tographic Films in Colors. PAUL FOURNIER, Feb. 11, 1930. (Class 95-2.) An 
objective with a sensitive surface in image-receiving relation thereto is utilized. 
A multicolor diaphragm provided with dividing lines between color areas is inter- 
posed between the objective and sensitive surface. 

1,749,278. Optical System for Use in Photographic Color Processes. CHAS. 
W. FREDERICK, Mar. 8, 1930. (Class 95-2.) Claim 10: "Complementary opti- 
cal systems for use in the taking and projecting of color photographs by the use of 
photographic layers having associated therewith numerous microscopic image- 
forming elements and comprising two objectives of different focal lengths, each 
system including one objective and a polychromatic screen associated therewith, 
and one system including a weak supplemental lens in front of its rear focal plane 
by a distance less than ten per cent of the focal length of the system, the positions 
of the screens in the systems being such that the virtual images thereof are of the 
same size and have the same positions relative to the rear focal planes of the 

1,750,358. Color Photography. PIERRE ABEL RICHARD, Mar. 11, 1930. 
(Class 88-16.4.) Claim 1: "In the production of motion pictures in color, the 
steps of photographing the objects on a moving film which is goffered on its front 
face with a multitude of minute lenticular projections, while subjecting the light 
rays to the action of a polychrome filter so as to select the colors of the rays which 
reach the film and thereby form images in polychrome corresponding to the colors 
of the filter; and thereafter reproducing the polychrome images of the goffered 
film on a non-goffered film while the former is illuminated, and advancing the 
non-goffered film, for each image-space of the goffered film, a number of image- 
spaces equal to the number of color values of the polychrome filter, while masking 
said filter in such a way as to permit the light to pass through only one of its 
colored elements for each image on the non-goffered film, to obtain on said non- 


goffered film a plurality of separate monochrome images of the polychrome image 
corresponding in number to the number of color values of said polychrome image." 

1,751,220. Light Filter. ICHITARO SHOJI, Mar. 18, 1930. (Class 95-81.5.) 

1,751,318. Process for Obtaining Photographic Images. EUGENE GAY, Mar. 
18, 1930. (Class 95-7.) Relating to the obtaining of a positive violet-red image. 

1,752,477. Camera for Color Cinematography. PERCY D. BREWSTER, April 
1, 1930. (Class 88-16.4.) Claim 1: "In a color camera, the combination with 
a lens, a film-gate in the rear of the lens to support a negative film in position for 
exposure, a plane mirror extending between the lens and said film-gate and occupy- 
ing a plane at an angle to the axis of the lens, said mirror having at least one 
light-passing opening, means for revolving the mirror in its own plane, a film-gate 
arranged to support a negative film in position to receive light reflected by the 
mirror, means for feeding films through the film-gates simultaneously step-by- 
step, a shutter for exposing both films at each period of rest thereof, and means 
for actuating the mirror, the shutter, and the film-feeding means in harmony with 
each other." 

1,752,680. Optical Means for Producing Color Cinematographic Pictures. 
KARL MARTIN AND PAUL TIETZE. April 1, 1930. (Class 88-1.) "In a device 
of the class described, a ray-dividing device comprising a partly light-pervious 
mirror, a pair of objectives arranged upon axes perpendicular to one another and 
positioned so that one objective receives directly the rays reflected from said 
mirror, while the other objective receives directly the rays transmitted through 
said mirror, means for passing a film perpendicular at its midline to the plane of 
said mirror, and optical means for turning the rays from said objectives into 
parallel contiguous paths registering respectively with the two halves of said film." 

1,753,140. Multicolor Cinematograph and Other Films. JOHN EDWARD 
THORNTON, April 1, 1930. (Class 88-16.4.) Claim 1: "A multi-color picture- 
positive having four component images in two half pictures and comprising two 
thin transparent supports of half thickness, one support bearing a half picture 
containing two component images, an image in one color upon each side of said 
support, and the other support bearing a half picture containing two component 
images, an image in one color upon each side of the other thin support, the two 
transparent supports being superimposed with the two hah* pictures assembled 
and disposed within one picture area and cemented together." 

1,753,379. Color Photography. WILLIAM V. D. KELLEY, April 8, 1930. 
(Class 95-2.) Claim 1: A photographic process which consists in forming a 
latent image in a light-sensitized coating on one side of a transparent carrier, de- 
veloping in acid diaminophenol, toning with an iron salt to a blue color and, after 
clearing with an aqueous bath of ammonium bromide and potassium bichromate, 
forming an image in the same coating and an image in a like coating on the other 
side of the transparent carrier and coloring said last formed images, one a magenta 
and the other a yellow, while preventing the coloring matter for one image from 
coming in contact with the other image." 

1,754,323. Color Projection Apparatus for Cinematographs. REGINALD 
KILLICK, April 15, 1930. (Class 88-16.4.) Relating strictly to the apparatus. 

1,757,852. Color Screen. CARL ALSTRUP AND VIGGO JBNSBN, May 
1930. (Class 88-164.) "In an apparatus for producing pictures in natural 


colors, a rotatable disk having a plurality of color filters and opposed shutter seg- 
ments dividing the filters into two groups, one group being composed of red and 
orange filters and the other group of yellow, green, blue, and violet filters, the 
tangential lengths of the red and orange filters being greater than the length of 
the other filters in proportion to the optical effectiveness of the colors whereby the 
latter produce equal impressions upon the eye." 

1,758,137. Apparatus for Printing Reticulated Films. RODOLPHE BERTHON, 
May 13, 1930. (Class 88-24.) 

1.758.184. Manufacture of Multicolor Cinematograph Films. JOHN EDWARD 
THORNTON, May 13, 1930. (Class 95-2.) Claim 2: "The method of producing 
a multi-width, multi-layer cinematograph colloid film positive comprising coating 
a temporary re-inforcing backing with colored colloid arranged in a plurality of 
parallel strips, sensitizing the colloid, printing component images one at a time 
in a straight line across the multi-width film, severing the film into a plurality of 
strips of single-width, removing the paper re-inforcement, cementing the printed 
colored strips together in accurate register and adding a layer of waterproof 

1.758.185. Cinematograph Color Film and Method of Manufacture. JOHN 
EDWARD THORNTON, May 13, 1930. (Class 95-2.) Claim 1: "The method of 
manufacturing a strip of film material which consists in coating a strip of celluloid 
with a thin layer of insoluble bichromated gelatin, applying thereto two strips of 
sensitized colloid, drying and shrinking the same, coating a strip of porous paper 
with a thin layer of soluble gelatin, drying and shrinking the same, damping the 
face of the two strips and laying one strip on the other to amalgamate them into 
a single strip of film material." 

1,758,572. Process of Producing Pictures Consisting of Dyes in Photographic 
Manner. FRIEDRICH LIERG, May 13, 1930. (Class 95-6.) 

1.758.768. Multicolor Cinematograph and Other Film. JOHN EDWARD 
THORNTON, May 13, 1930. (Class 95-2). Claim 1: "A double-width, multi- 
color, screen-mosaic picture positive comprising a double width film of trans- 
parent material, a color-mosaic screen in two colors covering each half width of 
the double- width film, an adhesive substratum between each color-screen and each 
half width of the film, and a half picture of negative character upon each half 
width of the film superimposed on its own color-screen." 

1.758.769. Multicolor Cinematograph and Other Film. JOHN EDWARD 
THORNTON, May 13, 1930. (Class 95-2.) 

1,758,977. Reflecting Prism. THOMAS W. ROLPH, May 20, 1930. (Class 
88-1.) A prism so constructed as to reflect a light ray at least three times in the 
same plane. 

1,759,914. Method of Producing Film for Color Cinematography. ALEX- 
ANDER PILNY, May 27, 1930. (Class 88-16.4.) Claim 1: "A method of pro- 
ducing film strips for cinematography which comprises splitting a series of images 
rectangularly and projecting them onto longitudinal parallel portions of a film 
strip by folding the strip longitudinally at right angles to present said portions for 
receiving the partial images." 

1,761,361. Control-Mechanism for Color Projecting Machines. ANTON J. 
OBERG AND ROBERT R. STOEFEN, June 3, 1930. (Class 88-24.) Relating 
strictly to the construction of the projecting machine. 


1,761,897. Multicolor-Cinematographic and Other Film and Process of Mak- 
ing Same. JOHN EDWARD THORNTON, June 3, 1930. (Class 95-2.) Claim 1: 
"A method of producing multi-colored cinematograph film positives upon double 
width transparent material of half standard thickness consisting in simultaneously 
coating one half width of the double width material with a sensitized colloid con- 
taining dye of one color and the other half width with a sensitized colloid contain- 
ing dye of a different color, photographically printing on each half width a partial 
image, washing off the surplus colored colloid, recoating each half width of the 
support with a differently colored sensitized colloid, which also differs in color 
from the colors in the first coating, printing on each half width a second partial 
image in the same picture space as the first partial image, washing off the surplus 
colloid, dividing the strips longitudinally, superimposing the two divided strips 
with their partial images in register and cementing them together to produce a 
complete picture in four colors in a single picture area." 

1.762.143. Filter and Method of Preparing Same. JOHN G. CAPSTAFF, June 
10, 1930. (Class 95-81.5.) Method of manufacture of a filter and of applying 
a color solution to the surface of a transparent plate. 

1.762.144. Lens System for Color Photography. HAROLD N. Cox, June 10, 
1930. (Class 88-1.) 

1.762.932. Projection System for Color Pictures. JOSEPH MIHALYI, June 10, 
1930. (Class 88-16.4.) 

1.762.933. Projection System for Color Pictures. JOSEPH MIHALYI, June 10, 
1930. (Class 88-16.4.) 

1,764,083. Color Guide. WILLIAM J. MISKELLA, June 17, 1930. (Class 41-6.) 
1 ,768,795. Dye-Carrying Layer for Photographic Films and the Like. SAMUEL 
E. SHEPPARD AND JAMES G. McNALLY, July 1, 1930. (Class 95-9.) 

1.768.812. Method of Producing Light Effects. WILLIAM J. WHITING, July 
1, 1930. (Class 88-1.) Claim 1: The method of producing two coordinate dif- 
fering visual effects which includes the steps of projecting upon an object objec- 
tively homogeneous asto color, a plurality of beams of subjectively similar light, said 
beams having an invisible spectral difference and substantially the same spectral 
center of gravity, said object having a spectral center of gravity different from that 
of the beams, whereby, when either beam strikes the object, its subjective color 
will change. 

1.768.813. Method of Increasing the Chroma of a Color. WILLIAM J. WHIT- 
ING, July 1, 1930. (Class 88-1.) 

1.768.814. Method of Reducing Glare and Dazzle of an Opposing Light. 
WILLIAM J. WHITING, July 1, 1930 (Class 88-1.) 

1,769,041. Color Filter and Process of Manufacturing the Same MERRILL 
W. SEYMOUR, July 1, 1930. (Class 95-81.5.) 

1,769,940. Manufacture of Light-Sensitive Films. ULRICH DIBM-BERNBT, 
July 8, 1930. (Class 95-9.) Claim 1: "A process for producing light 
negative and positive films having no coating, which consists in incorporating 
sensitizing agents in the film mass of viscose during the manufacture of the film 

1,771,029. Motion Picture Film and Method of Producing. JAKOB BURK- 
HARDT, July 22, 1930. (Class 88-16.) This invention relates to third dimension 


1 ,772,081. Process and Apparatus for Treating Derivatives of Aqueous Cellu- 
lose Compounds for Use in Photographic and Its Allied Arts and Other Useful 
Purposes. FREDERICK W. HOCHSTETTER, Aug. 5, 1930. (Class 91-69.) 

1,772,622. Motion Picture Color Photography. PIERRE M. ARTIGUE. Aug. 
12,1930. (Class 88-16.4.) Claim 1: "The herein described method of coloring 
motion picture films which consists in mounting a positive film upon supports that 
are threaded through the apertures at the sides of the film so that certain of the 
frames of the film are disposed on one side of the supports and the other frames 
on the other side of said supports, then coloring the frames of said film on one 
side of said supports and then distinctively coloring the frames of the film on the 
other side of said supports." 

1,775,938. Color Photography. ISIDOR KITSEE AND DUFF C. LAW, Sept. 16, 
1930. (Class 95-81.5.) Claim 1: "The method of coloring the interstitial por- 
tion of a celluloid film, one side of which is provided with a developed emulsion in 
transparent colored figurations in relief and with minute interstices between said 
figurations extending to the surface of said film, which consists in removing sub- 
stantially all the air from said interstices and then applying to said side of said film 
a liquid coloring matter dissolved in a solvent of celluloid in which the material 
of said emulsion is not soluble, the color of said liquid being complementary to 
that of said figuration." 

1,778,139. Positive Motion-Picture Film. ROBERT JOHN, Oct. 14, 1930. 
(Class 88-19.5.) Claim 1: "A motion picture transferring film of the dye transfer 
type having an image comprising minute color dots in great numbers and more 
sparsely grouped in the lights and more densely grouped in the shades and being 
grouped irregularly according to the lights and shades of the original object 
photographed, and representing a naturally photographic record thereof, said 
dots and grouping thereof being of such character as to present an apparently 
unbroken image when projected at above 50 diameters enlargement." 

1,778,754. Optical System HAROLD N. Cox, Oct. 21, 1930. (Class 88-1.) 
"In apparatus for color photography the combination of a frame, a negative lens 
element borne by said frame, a plurality of objectives also borne by said frame 
and to the rear of said negative lens element and symmetrically arranged with 
respect to the axis thereof, a telescopic lens barrel borne by said frame, and a 
positive lens element borne by said lens barrel coaxially with the negative lens 
element aforesaid and arranged in front thereof." 

1,780,260. Method of Producing Pictures in Colors. GEORGE F. CAPWELL, 
Nov. 4, 1930. (Class 101-115.) Claim 1: "The method of producing pictures 
in colors, which consists in interposing a protective screen over the surface to 
receive the picture and beneath a screen stencil, and forcing a color through the 
stencil and protective screen." 

1,781,496. Apparatus for Color Photography. HAROLD N. Cox, Nov. 11, 
1930. (Class 88-1.) 

1,782,288. Projecting Apparatus. ROHAN CLUFF, Nov. 18, 1930. (Class 
88-24.) Claim 1: "A projecting apparatus comprising a set of shadow forming 
elements, a series of light receiving and reflecting elements, one spaced from the 
other and said elements arranged tandemwise rearwardly of said shadow forming 
elements, certain of said receiving and reflecting elements having light sources of 
different colors, means for revolving said elements approximately 1500 revolu- 


tions per minute, a telescope arranged adjacent to tin- inmr one of said light 
receiving and reflecting elements, and a light confining means for said elements 
and extended upon the telescope at the entrance end of the latter." 

1,783,045. Contact Film Printer. EDWARD W. KELLOGG, Nov. 25, 1930. 
(Class 95-75.) A method adapted to allow printing where a plurality of films 
have different degrees of shrinkage. 

1,783,998. Photographic Reproduction Objective with Two Diaphragms and 
Its Application as in Printing Positives for Black and White Cinematography, 
Color Cinematography, or Cinematography in Relief. HENRI CHRETIEN, Dec. 9, 
1930. (Class 88-24.) Claim 10: "An apparatus for photographically repro- 
ducing cinematographic films including two separate and distinct objectives 
located side by side and having diaphragms, and optically intermediate conver- 
gent optical means adapted to form the image of the diaphragms and a pair of 
reels on the same identical drive shaft and disposed in front of the objectives, 
said reels carrying the film to be reproduced and the sensitized film, respectively." 

1,784,758. Cellulose Film. SAMUEL E. SHEPPARD AND JAMES G. MCNALLY, 
Dec. 9, 1930. (Class 95-9.) Claim 1: "A substantially flat laminated cellulose 
ester film comprising at least two laminae having the grain of one lamina at an 
angle to the grain of the adjacent lamina." 

1,785,997. Method of Securing Accurate Color Values in Color Printing and 
Color Photography. CARL BLECHER, Dec. 23, 1930. (Class 95-2.) Claim 1: 
"A method for securing accurate color values in color printing and color photog- 
raphy, characterized by the feature that for the colored part images to be placed 
together intermediate images are made in the respective colors on thin films 
stretched on frames.' 

1,787,023. Camera and Method of Photography. JOHN F. SEITZ, Dec. 30, 
1930. (Class 88-16.) Claim 1: "A combination camera and projector com- 
prising a camera structure having a main lens, a film holder to receive light 
directly through the lens on the film, an auxiliary lens in the side of the camera, 
means to reflect light passing through the auxiliary lens on the back of the film, 
and a lamp holder secured in the side of the camera and shiftable to replace the 
auxiliary lens in relation to the reflector whereby light may be projected from the 
holder and reflected through the film and through the main lens." 

1,787,201. Combined Black and White and Colored Image Photography. 
WILLIAM V. D. KELLEY, Dec. 30,1930. (Class 95-2.) Claim 1: "A transparent 
carrier coated on one side only with gelatin having a reduced silver image of the 
minus reds in the original subject and a toned color representation of the red in 
the original subject." 


Class 8 Bleaching and Dyeing. 
1. Carbon dyes. 

5. Dyeing processes. 

6. Dyes. 

Class 18 Plastics. 

57. Film spreading. 


Class 34- Dryers. 

48. Web. 

Class 41 Ornamentation. 

6. Painters' mixing charts. 
21. Surface Type diaphanous. 

42. " " etching. 

43. " resist preparation. 

Class 88 Optics. 

1. Miscellaneous. 

16. Motion Picture Apparatus. 
16.4 " " color. 

18.4 intermittent grip type. 

19.5 " picture vehicles and elements. 
24. Projecting Apparatus. 

Class 91 Coating. 

Special Machines 
10. Photographic film and plate. 

69. Photographic film and plate. 

Class 95 Photography. 

2. Color. 

6. Sensitizing and developing. 

7. Sensitizing. 

8. Sensitized elements. 

9. Films. 

75. Printing continuous film. 

81.5 Screens color. 

88. Developing. 

89. Fluid Treating Apparatus. 

90.5 " " " roll film. 

94. " " " film guides. 

Class 101 Printing. 

115. Multicolor. 
127. Stencil plates. 
130. Planographic. 

149. processes. 

150. Intaglio. 

182. Interrupter. 

Printing Members 
395. Plates. 

Class 154 Laminated Fabric and Analogous Manufactures. 
40. Fabric coating and uniting processes. 

Class 193 Conveyors Chutes, Skids, Guides, and Ways. 
2. Chutes. 


Class 204 Electrochemistry. 

9. Chemicals. 

Class 242 Winding and Reeling. 

Reeling and Unreeling 
55. Fabrics. 
77. Reels. 

Class 271 Sheet or Web Feeding or Delivering. 

23. Bottom Feed. 

Respectfully submitted, 




W. V. D. KELLEY, Chairman 


This Committee was late in getting organized and has, therefore, 
been able to hold only one meeting for discussion of its program and 
division of labor among its members. 

Because of the fact that this is the first Projection Theory Com- 
mittee, the boundary lines separating its proper sphere of activity 
from the subject matter appropriate to several other committees is 
not definitely established, so that in the choice of material for con- 
sideration there is apt to be a certain amount of overlapping of the 
work of these committees. In so far as reports of facts are concerned, 
this overlapping would be objectionable only if the various com- 
mittees did not agree but in so far as concerns matters of opinion, we 
see no particular objection to a moderate amount of overlapping, 
and, on the other hand, feel that even some advantage might be 
derived from it. 

In a general way, the work of this Committee deals with the opti- 
cal and mechanical principles of the mechanism by which a picture 
is projected on the screen, with the character of the image on the 
screen, and with its effect on the observer. It does not concern 
itself with the lay-out or operation of the projection room, with the 
characteristics of the screen, or with sound reproduction. The range 
of interests of the Committee can scarcely exclude consideration of 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 


the brightness of the projected picture in relation to its effect upon 
the observer, although our consideration of this subject overlaps some 
of the proposed activities of the Projection Screens Committee. 

Since this Committee is new it seems appropriate to begin with a 
summary of existing literature. Such a summary should serve as a 
basis for the future activities of this and succeeding committees, 
and the work involved in formulating it has been undertaken by a 
subcommittee headed by Mr. H. P. Gage. In addition to a sum- 
mary of the literature, the Committee intends to call attention to 
and to comment on proposed types of projection which may differ 
from current practice. 

Several members of the Society are interested in the development 
of non-intermittent projectors. Papers dealing with these have from 
time to time been presented and demonstrations of such projectors 
have been made before the Society. The Committee feels that these 
efforts deserve recognition. There is no doubt that the future welfare 
of the motion picture industry will depend upon the quality of pro- 
jection as much as upon other factors. The designers of non- 
intermittent projectors are striving for picture quality superior 
to anything now obtained with the ordinary intermittent projector. 
The success of non-theatrical motion pictures depends in a large 
measure on the cost of equipment and operation, and the designers 
of non-intermittent projectors are convinced that in the field of the 
16 mm. projector this type of projection has promise from the stand- 
point of economy. 

It is claimed that pictures projected with continuously moving 
film and an uninterrupted light-beam will produce less eye-strain 
and systemic fatigue than the current intermittent system. The 
Committee does not feel competent to express an opinion as to 
the soundness of this claim. Reference will be made later to this 

In addition to the possibility of improving the quality of the pro- 
jected picture, it is claimed that non-intermittent projectors provide 
the following mechanical advantages: 

(1) low cost of maintenance; 

(2) longer life of film ; 

(3) silent operation; 

(4) advantages in reproducing sound from film; 

(5) special adaptability to the reproduction of color by the 
additive process. 


In elaborating items 4 and 5, it may be said that it seems obvious 
that certain types, at least, of non-intermittent projectors permit 
higher film speeds than are practical with the intermittent type. 
While this leads to a greater cost of film, it would help overcome the 
difficulty of recording high frequencies on 16 mm. film sound track. 
In color process work it would permit the super-position (due to 
persistence of vision) of two or more appropriately colored views 
of each frame from a single print. 

The Committee believes that these claims, in general, are sound. 
However, in making this statement, it wishes to be understood that 
it is not referring to any particular non-intermittent projector. The 
Committee has made no study of individual proposals and does not 
feel that it lies within its legitimate range of activities to do so. It 
is merely stating that it believes in general that non-intermittent 
projection systems possess the possibility of realizing the mechanical 
advantages enumerated above. 

The plan of projecting motion pictures from behind the screen has 
been revived and has received considerable attention during the 
past year. From the standpoint of the manufacturer of 16 mm. 
projectors and from the standpoint of economy in the design and 
operation of small theaters showing 35 mm. film, it has advantages. 
In the 16 mm. field it makes possible self-contained cabinet model 
machines; in the theaters it is economical of space. 

In order to realize important economy of space in both these 
applications it is essential that the projection distance be reduced 
to the least possible value compatible with an image which is satis- 
factorily sharp and sufficiently bright. This requirement imposes 
extraordinary demands on the designer of the optical systems in- 
volved and, to some extent, on the maker of incandescent lamps. 
Since the decrease in projection distance, for an image of constant 
size, can generally be accomplished only at the expense of definition 
or brightness, or both, the extent to which this decrease may be 
carried is always a matter of judgment. Incorrect judgment may 
involve considerable financial loss. If the Society of Motion Picture 
Engineers could formulate fundamental principles on the basis of 
which such judgments could be formed it would be rendering the 
industry very valuable service. 

The Committee is impressed with the desirability of increasing 
the horizontal angle of view in motion picture practice, 
ods of accomplishing this have been proposed of which the most 


discussed is that of using the so-called "wide film." The wide-film 
problem has been studied by the Committee on Standards and 
Nomenclature so thoroughly that this Committee will give it no 
further attention. In this statement the expression "wide film" is 
to be understood to cover all forms of reduction printing from a 
wide-film negative as well as the proposal that the picture occupy 
the space of two frames on the film, rotated 90 degrees by the camera 
and the projector by means of appropriate optical elements. 

Another device has been proposed for accomplishing the same 
result, in which horizontal dimensions are compressed in photo- 
graphing and expanded by an equal amount in projection by means 
of anamorphotic systems. Systems of cylinders and of Brewster 
prisms have been attempted. The optical difficulties of equaling 
the picture quality obtained by using "wide film" are believed by 
the Committee to be insurmountable. When analyzed optically, 
this plan involves lenses whose focal length in the vertical meridian 
is longer than in the horizontal meridian but whose focal point is the 
same for both meridians. If satisfactory performance is possible in 
the horizontal meridian a symmetrical lens is also possible whose 
focal length is the same as that in the horizontal meridian in the case 
of both the camera and the projection lens. The use of these com- 
parable short focus symmetrical lenses would, by reason of their 
greater ease of manufacture and manipulation, result in better defini- 
tion, but probably in less screen illumination. Assuming that satis- 
factory designs of the anamorphotic systems were possible, it is a 
question whether the greater difficulty involved in getting satisfac- 
tory illumination with the short focus symmetrical lenses would not 
be compensated by the very much less difficulty of manufacture and 

It remains also to be pointed out that should it be possible to 
design an anamorphotic lens system for a given object distance it 
would be optically impossible to maintain the coincidence of focal 
points for vertical and horizontal meridians for any other object 
distance. Such a lens system must always theoretically yield an 
astigmatic image except for the one object distance for which it is 

At the meeting of the Committee, considerable discussion developed 
on the subject of the fatigue involved in viewing motion pictures. 
It is a matter of more or less common popular belief that more visual 
fatigue is experienced in viewing a motion picture program than is 


experienced in the ordinary employment of the visual function. 
This opinion has been accepted generally by the motion picture- 
industry. It has been attributed to a variety of causes. The de- 
signers of non-intermittent projectors claim that the alternation of 
light and darkness on the screen, in spite of the fact that it occurs 
so rapidly that it is imperceptible, is responsible for visual fatigue. 
Others attribute fatigue to such factors as flicker, insufficient illu- 
mination in the projected picture, excessive illumination in the pro- 
jected picture, contrast with the surrounding field, and poor focusing 
of the projected picture. Some of the various methods for pro- 
jecting motion pictures in natural colors are regarded as more 
fatiguing to view than others. 

In so far as we know, very little quantitative work on the fatigue 
involved in viewing motion pictures has been done, and yet nothing 
seems more important to the future welfare of the industry than the 
study of this problem. Excellent and valuable research work is 
being carried on by private organizations and individuals within the 
industry but the inherent difficulty of some of the problems involved 
is so great as to deter such agencies from attacking them and to 
prevent them from making sufficiently rapid progress. It is a 
question whether objective methods exist by means of which visual 
and systemic fatigue developed on viewing motion pictures can be 
measured. The development of such methods can probably only 
be accomplished with the cooperation of ophthalmologists, physiolo- 
gists, psychologists, and physicists. 

It is the suggestion of this Committee, therefore, that the Society 
of Motion Picture Engineers attempt to interest a suitable educa- 
tional institution to undertake research work along this line. It is 
further suggested that the University of Rochester is admirably 
equipped as to personnel to undertake such research at its Institute 
of Optics, for it has available on its faculties outstanding men in 
all the categories listed above. In addition, it also is in a position 
to secure the cooperation of the Eastman Kodak Company and the 
Bausch & Lomb Optical Company. It is suggested, therefore, that 
the Society approach the University of Rochester, urging it to take 
up research work along this line. There is no doubt that the accu- 
mulation of data of this sort would be slow, on account of the diffi- 
culty of the problem, but the Committee believes that it is the only 
sound way to establish a basis for a future projection theory. 

It is thought probable that the only way in which this work could 


be inaugurated would be by the establishment at the University of a 
fellowship supported by some individual or organization in the motion 
picture industry. In discussing this with the director of the Institute 
of Optics, he expressed the belief that the first year's work could 
hardly be more than exploratory, that is, a study of the possibilities 
of various methods of attack, with a view to discovering what 
methods, if any, can be devised for obtaining the desired information. 
Such a preliminary exploration might be conducted by a graduate 
student operating under the director of the Institute, who, in turn, 
would consult with the departments of medicine, physiology, and 
psychology of the University and with this Committee. 

It is by no means certain that it will be possible to find a quantita- 
tive expression for the fatigue experienced in viewing a motion 
picture, assuming that such a phenomenon exists. There is no 
doubt, however, that great profit would accrue from such informa- 
tion, substituting it for the mass of personal opinion which now 
exists and which at present serves as the only basis on which to 
decide questions of projection theory. 




C. TUTTLE K. F. Moss (Advisory) 

W. B. RAYTON, Chairman 


At a meeting held May 13th in the Paramount Bldg., New York, 
N. Y., the following resolution was made and passed: 

"Whereas, the Standard Release Print has been in widespread use during the 
past several months and has resulted in the reduction of film mutilation and 
the elimination of punch-marking of film for change-over purposes, and 

"Whereas, the Standard Release Print has contributed to improved change- 
overs and smoother performances 

"Therefore, be it resolved that the Projection Practice Committee go on record 
as endorsing the said Standard Release Print as a practical step in the improve- 
ment of projection." 

H. RUBIN, Chairman 


Wide-Field Pictures on Narrow Gauge Film. FRED SCHMID. Amer. Cinema- 
tographer, XII, May, 1931, p. 36. A novel auxiliary lens system, designed by 
S. H. Newcomer, consists of cylindrical lens elements which are to be usi-d with 
photographic or projection lenses. The system has a magnification of !..'> in 
the horizontal plane only. Its effect is thus to increase by 50 per cent the hori- 
zontal angular covering power of any lens with which it is used. This extra 
field is compressed into the standard aperture width in photography, and magni- 
fied to normal proportions when the system is used on the projection lens. Units 
designed for 16 mm. film are now on the market, made by the C. P. Goerz Ameri- 
can Optical Company of New York. They are said to require about 15 per cent 
more exposure than standard photographic lenses, and to reduce illumination 
in projection by one-third. A. A. C. 

Super-Sensitive Film in Production. OLIVER MARSH. Amer. Cinematog- 
rapher, XII, May, 1931, p. 11. The advantage of increased speed of the new 
film is said to be of secondary importance to the improved quality made possible 
by a better rendition of color and tone values. The results achieved seem to 
furnish a much closer approach to the natural visual brilliancy of the scene than 
has been reached with other materials. The author points out that, while less- 
light is needed on the set, reduction must not be made in such a way that the 
normal balance of the lighting is disturbed. A certain number of light sources 
are needed for the balanced lighting of any set. A reduction in illumination 
should be made by using smaller lamps in present equipment; reducing the 
number of units is liable to spoil the quality of the picture. A. A. C. 

Noiseless Test Film Developed by ERPI. T. L. DOWEY. Amer. Cinematog- 
rapher, XII, May, 1931, p. 27; Mot. Pict. Projectionist, IV, May, 1931, p. 23. 
The new test film has no picture, but has two sound tracks which include voice 
and music selections, several constant-frequency sections from 55 to 8000 cycles, 
and a length of unmodulated track for ground noise measurement. It may be 
used to check the general quality of the theater sound reproducing system or to 
determine the frequency characteristics, and is expected to be a valuable standard 
for comparison of theater installations. The two tracks are recorded from 
opposite ends so that rewinding is unnecessary. A. A. C. 

The Unsound Sound Business. HENRY L. WILLIAMS. Proj. Eng., HI, 
May, 1931, p. 9. Attention is called to the haphazard merchandising methods 
of manufacturers of sound equipment, which are claimed to be retarding in- 
fluences on the growth of the industry. The author recommends that manu- 
facturers sell only to reliable engineers who can help the factory control the use 
of their product and assume part of the responsibility for satisfactory service. 
A definite policy of this kind is advised as a necessary basis for prosperity in 
the industry. A. A. C. 

Some Optical Features in Two-Way Television. H. E. IVBS. BeU System 


136 ABSTRACTS [J. S. M. P. E. 

Tech. J., April, 1931, p. 265. Improvements in the optical systems of both the 
receiving and sending ends of an experimental two-way television system are 
explained. The scanning beam of the usual television system is of such intensity 
that it interferes with the users' vision of the incoming picture. By using a 
purple scanning beam and blue-sensitive potassium and red-sensitive caesium 
photoelectric cells, this objection is greatly reduced. In the receiving end the 
usual Nipkow disk has been replaced by a disk in which each of the spiral holes 
has an associated condensing lens fixed so as to focus, in combination with a 
fixed collimating lens, an image of the source on the disk hole. A. H. H. 

Condenser Loud Speaker with Flexible Electrodes. P. E. EDELMAN. Proc. 
I. R. E., Feb., 1931, p. 256. The author describes a condenser loud speaker 
built of a flexible impregnated cloth carrying a conductive coating and an air- 
permeable electrode, also flexible. The air space is regulated by means of thread 
spacers, which also tend to reduce back-lash rustle common to speakers of this 
type. Several operating circuits using this device either as a reproducer or as 
a pick-up unit are illustrated. Best results are obtained when these circuits 
compensate for the response characteristics of the speaker unit. A. H. H. 

World's Biggest Cinema. Kinemat. Weekly (Ideal Kinema Supplement] , 
168, Feb. 12, 1931, p. 5. Describes the reconstruction work on the Gaumont 
Palace, Paris, which is one of the world's largest theaters. The ground floor 
has been lowered to the street level, and the mezzanine and upper balcony, 
which seat 900 and 1000 persons, respectively, are carried without any visible 
supporting column. These galleries are supported from each end by a metallic 
bridge resting on two abutments for which it was necessary to carry the founda- 
tions down nearly 100 feet. The total seating capacity of the theater will be 
6000. The projection room, covering 900 square feet, will be equipped with 
six lanterns and six projectors, with plenty of room for future installations. It 
is estimated that 3000 amperes at 110 volts will be required by the projection 
room. Power will be furnished by Diesel engines. H. P. 

Acoustics in Kinema Design. C. W. GLOVER. Kinemat. Weekly (Ideal 
Kinema Supplement], 168, Feb. 12, 1931, pp. 7-11. A certain amount of rever- 
beration is desirable in theaters since it reenforces the direct sound, but excessive 
reverberation so changes the effective sound wave that speech becomes un- 
intelligible. In the case of reproduced sound a certain amount of reverberation 
is introduced in the studio recording; moreover, the sound is reproduced at a 
considerably higher level than the original, and calculations based on the Sabine 
formula give values too great. Echoes also tend to render the sound unintelli- 
gible. In theater design, curves should be avoided as far as possible, although 
ingenious devices have been used successfully to break up the reflections from 
curved walls and domes. 

Acoustical materials offer difficulties because of their poor fire-resistant prop- 
erties. If air spaces are used behind the absorbent material, great care should 
be taken to see that they are completely closed and do not form continuous 
chimneys. If it is necessary to color the absorbent, stains should be used which 
will not clog the surface pores as would paint. Dust will also clog the pores so 
that cleaning of the theater should be extended to the acoustical linings. H. P. 

Technicolor Benefits by New Process. F. POPE. Mot. Pict. Daily, 29, 
May 11, 1931, p. 1. Freedom from the "boiling grain" effect in white areas on 

July, 1931] ABSTRACTS 137 

projection of color prints is claimed as a result o an improvement in this sub- 
tractive process. Better definition is obtained on long shots than was pre- 
viously possible. Super-sensitive film has made possible a decrease of lighting 
necessary for exposing color pictures. G. E. M. 

New Fireproof Film Cabinet Demonstrated. Mot. Pict. Daily, 29, Apr. 11, 
1931, p. 1. The cabinet is designed to hold eight 2000-foot reels of film pre- 
sumably in an exchange or a projection booth. It is built to withstand a great 
deal of heat. Both external and internal fire tests are described indicating the 
heat insulating properties of the walls. Technical construction details are not 
given. G. E. M. 

New ERPI Photoelectric Cell Cuts System Noise. Mot. Pict. Daily, 29, 
Apr. 21, 1931, p. 7. Caesium oxide is coated on a half-cylindrical electrode and 
a small vertical rod forms the anode. The previous cell used potassium as the 
light-sensitive element. Since the response of the cell is greater, the amplifiers 
can be operated with reduced gain, thus reducing the volume level of noise within 
the system. Other improved features are cited. G. E. M. 

Testing Sound on Negative. M. F. COOPER. Kinemat. Weekly Supp., 170, 
Apr. 16, 1931, p. 25. Describes a method for determining the amount of de- 
velopment which has been given a variable width sound record independently of 
the exposure given the negative. Photographic requirements which must be 
satisfied by a good variable width sound negative are: (1) its image density 
should be about 1.4 and its fog density not more than 0.07; (2) the exposure 
should have been such that on development to a gamma of 2.0, the image density 
will be as given under (1). Two ways of giving such a film a known exposure 
of varying amount are (1) by adjusting the exciter lamp current, and (2) by 
varying the speed of the recorder. The second is, perhaps, the simplest. The 
oscillograph is supplied with a weak alternating current of constant frequency, 
of such value as to modulate the track just perceptibly. The machine is then 
set in motion, turned off, and allowed to come to rest of its own accord. As 
the recorder slows down, the exposure increases, and the frequency of the de- 
veloped wave form is proportional to the exposure. The distance between the 
peaks of the wave is measured with a scaleometer and the logarithms of the 
reciprocals of these values are plotted as proportional to the relative exposures. 
Densities at these points are measured, and when plotted against the relative 
exposures a value for the gamma is obtained. An example of the method is 
given. G. E. M. 

New Metal Mesh Theater Screen. Film Daily, 55, May 17, 1931, p. 7. It 
is claimed that very satisfactory results have been obtained using a new type 
metal mesh theater screen. The features claimed for this screen include: a 
chemically treated surface free from all gloss, a very high reflection factor, and 
clear and uniform sound distribution throughout the entire theater. The sur- 
face can be washed with hot water and a soft brush without causing injury. 
The screen is stated to afford a clear view of any picture from any angle of ob- 
servation, eliminating eye-strain and distortion. The screen surface may be 
periodically sprayed and for this purpose the company plans to lend, for a period 
of ten years, a complete spraying outfit with each screen purchased and furnish 
chemical solutions for resurfacing the screen. 

Motion Pictures in the Service of Technical Research. F. DARDIN. Kino- 


technik, 13, Feb. 5 and 20, 1931, pp. 40-43 and 65-67. A vertical form 
of the Ruth boiler for storing steam to equalize power loads in industries was 
studied by means of motion pictures of a laboratory model of glass. A type of 
construction preventing undue ebullition of the water and consequent carrying 
out of water in the steam during discharge of the boiler was arrived at as a result 
of this study. A mercury arc rectifier was also studied by motion pictures 
under conditions where direct observation would have been impossible on ac- 
count of the danger of bursting the glass. The operation of an automatic train- 
stopping device and the manufacture of "Protos" vacuum cleaners were also 
filmed. M. W. S. 

Correctoscope. Movie Makers, 6, May, 1931, p. 287. This new camera 
accessory is a combined range finder and exposure meter. It consists of a highly 
corrected lens, a reflecting prism, and a magnifying eyepiece which is adjustable 
for any particular eye condition. To find the range, the focusing ring is turned 
until the magnified image is sharp and the distance is read directly from the 
scale or, with non-turret cameras equipped with certain lenses, the instrument 
can be geared to the camera lens so that both operate simultaneously, enabling 
subjects moving toward or away from the camera to be kept in focus. To 
determine the correct exposure, a special filter is slipped into place and the dia- 
phragm adjusted until detail in the shadows just disappears. The proper stop 
is then read directly, requiring no calculations. H. P. 

Psychological Acoustics and Sound Films. G. KOGEL. Kinotechnik, 13, 
Feb. 5, 1931, p. 39. In sound film presentations it is disturbing to have the 
sound come from a direction different from that which would be expected from 
the action on the screen. If, however, the sound is produced in such a manner 
that it is impossible to distinguish the actual direction of its source, it will be 
associated with the proper location on the motion picture screen as a result of 
certain psychological reactions. This view is upheld by analogy with ventrilo- 
quism and the illusion of motion on the screen. M. W. S. 


Carrigan, J. B. MacNair, W. A. 

Cook, A. A. Matthews, G. E. 

Crabtree, J. I. McNicol, D. 

Haak, A. H. Meulendyke, C. E. 

Hardy, A. C. Muehler, L. E. 

Herriot, W. Parker, H. 

Irby, F. S. Sandvick, O. 

Ives, C. E. Schwingel, C. H. 

Loveland, R. P. Seymour, M. W 

MacFarlane, J. W. Wyerts, W. 


1,796,725. Focusing Finder. O. A. Ross. March 17, 1931. An attach- 
ment for cameras whereby a motion picture photographer may, if desired, 
simultaneously photograph, focus, and observe the field being photographed, 
the delineation of the field or frame in the finder being substantially identical 
to the delineation of the frame being photographically impressed on the motion 
picture film at the photographing aperture in the camera. The photographer 
views a magnified field through a view finder section comprising a finder hood, 
viewing lens, finder lens bracket, lens mount and lens, and focuses sharply on 
that field. If the finder lens barrel indicates six feet, not only will the photo- 
graphing lens be also sharply focused on the same field, but, in addition, the 
delineation of the field of the photographed field will be substantially the same 
as the delineation of the field seen on the viewing lens in the finder section. 

A photographer may view the desired field or frame through the view finder 
section and adjust the finder lens barrel for sharpness of image and preferably 
simultaneously move the camera with respect to the tripod or camera mount 
until the field or frame seen in the view finder is the desired one, thereafter, <>r 
simultaneously, operating the camera to photographically record the scene of 
the field or frame on the motion picture film. This performance may be accom- 
plished without referring to the distance numerals appearing on the finder barrel. 

1,801,268. Multiple Turntables for Aiding Disk Synchronization. FRANK 
L. DYER. April 21, 1931. A plurality of phonograph disk record turntables 
are provided in independent geared relation to the driving motor. The gearing 
between one phonograph turntable and the motor provides for normal turn- 
table speed. The gearing between another turntable and the motor provides 
for a slightly higher speed. A third gearing between another turntable and 
the motor provides for slightly lower speed. By providing all of the simul- 
taneously operating records, an operator in the projection booth who suddenly 
finds a condition of non-synchronism existing between the picture and the sound 
may overcome this condition by at once throwing into position the sound pick-up 
arms to register with either the faster running sound record or the slower oper- 
ating sound record, and therefore match the picture and sound without r 
ruption of the program. The multiple arrangement of phonograph turntables 
also provides means for running a continuous program without interruption and 
providing a musical program between picture reels. 

1,801,450. Optical Printing System. F. H. OWENS. April 21, 1 
printer for printing positive film strips from a multiplicity of negative film strips. 
Provision is made for driving the negative and positive film strips simultaneously 
by arranging independent sprockets on the same drive shaft. One of the sprockets 
is adapted to move the strip of positive film. Other sprockets engage s 
negative film. A system of prisms and lenses is provided so that images 
different portions of all of the negative strips may be directed upon the positive 


140 PATENT ABSTRACTS [J. s. M. p. E. 

strip for integrating upon the positive strip desired views obtained from the 
negative strips. The driving of all of the sprockets simultaneously from the 
same drive shaft insures synchronism in the printing process. 

1,802,045. Projector Adaptable for Motion and Still Pictures. J. BOGOPOL- 
SKY. April 21, 1931. A portable type of projecting machine which may be 
stopped in any position to project a still picture. The machine comprises a 
compartment containing a driving motor and a compartment at the front of the 
projector and above the motor compartment for containing a shutter and an 
intermittent film-driving means. Two compartments located side by side 
behind the shutter compartment are arranged to contain a light source and a 
resistance element. At the moment when the movement of the film ceases an 
anti-scintillating device becomes effective to filter the light in such manner as 
to avoid the transmission of heat to the film. 

1,802,248. Automatic Control Circuit for Projection Change-Over. R. M. 
GEYER AND CHARLES M. SWEET. April 21, 1931. A control circuit to motion 
picture projectors for permitting the screening in sequence of film reels without 
perceptible interruption in the projection between successive reels of film, in 
which a pair of switches is automatically operated by a solenoid united with a 
metal plate which cuts off the light beams from the lamp houses when the sole- 
noid is not actively energized, but which is clear of the path of light rays when 
the core of the solenoid is actuated. 

A mechanism is coupled with a plurality of motion picture projectors, in which 
a movable contact arm controlling the circuit is maintained in a position for 
keeping open the circuit through one of the units controlling the projectors, and 
retained in such "position by an edge of a film. The motor circuits and the 
light sources of each of the projecting machines are automatically controlled 
as the film in one projector nears the end of a reel to produce cooperative func- 
tioning of the adjacent projector in bringing about co-extensive operation of the 
machines without interruption. 

1,802,480. Projection Screen and Sound Reproducers. H. W. ROGERS. 
April 28, 1931. Motion picture projection screen which carries a frame structure 
in the rear for the mounting of a multiplicity of sound reproducers. The sound 
reproducers may each be adjustably positioned on the frame structure in the rear 
of the screen and arranged to direct sound through the screen through flared bell 
structures constituting parts of the sound reproducers. 

1,802,570. Illuminated Stage Setting for Projection Screen. J. W. OGLE- 
TREE. April 28, 1931. Screen for the reproduction of motion pictures wherein 
a stage setting is provided behind the screen and adjacent the sides thereof for 
illuminating the space adjacent the screen with light rays contrasting in color 
with that of the picture, the contrast between the picture and its background 
serving not only to reduce eye-strain but, by virtue of the blending between the 
light of the picture and that of the space in which it is situated, functions to 
create an impression of depth. The screen is mounted within a stage setting 
for receiving a picture of predetermined color tone. The background is diffused 
with a subdued colored light, the latter emanating from the back of the screen 
and being adapted to blend with the color tone of the picture to produce a soften- 
ing effect between the picture and the immediate vicinity of the screen. Lights 
are so arranged as to be shielded from the direct vision of the audience and yet 

July, 1931] PATENT ABSTRACTS 141 

produce that contrasting light effect which will relieve optical strain upon t he- 

1,802,595. Multiple Sound Tracks for Obtaining Long Records on Normal 
Length Film. LEE DEFOREST. Assignor to DeForest Phonofilm Corporation. 
April 28, 1931. A mechanism for reproducing sound from film where the film 
has a plurality of longitudinally extending sound records thereon. A light slit 
is provided in a block which is shif table laterally of the film. The film is driven 
past the slit block successively in opposite directions and the slit block moved 
to align the same successively with each sound record on the film upon each 
reversal in direction of the film. In this way a sound program of extended length 
is obtained from a film record of normal length. 

1,802,747. Kerr Cell Employing a Plurality of Elements and Electrostatic 
Fields. V. K. ZWORYKIN. Assigned to Westinghouse Electric & Manufacturing 
Company. April 28, 1931. A Kerr cell comprising a plurality of linear elec- 
trodes, interpositioned between the light source and a light-sensitive film. A 
sound modulating circuit has the output thereof connected to the electrodes of 
the Kerr cell and controls the operation of the Kerr cell for analyzing polarized 
light directed through the cell upon a light-sensitive film. The invention con- 
sists in subdividing each electrode of a Kerr cell into a plurality of electrode 
elements, and in so intercalating these elements that the incident light is sub- 
jected to a plurality of electrostatic fields during its travel therebetween in 
of being subjected to but a single field as in Kerr cells that were known to the 
prior art. In addition, a linear source of light is so related with the Kerr cell 
that each portion of the light beam is subjected to a separate electrostatic field. 

1,802,530. Method and Device for Producing Color Films. OTTO PILNY 
AND ALEX PILNY. April 28, 1931. Color film which is produced from two 
series of component color pictures arranged in close proximity on one film pro- 
jected by means of a single source of light utilizing a mechanical separation of 
the beams, while avoiding any crossings of the path of the beams, to the front 
and back of a second film sensitized on both sides so that the two pictures coincide 
with each other. The first film carries closely adjacent pairs of correlated 
pictures through which parallel rays are projected, and separately and simul- 
taneously focused to different optical reflecting systems and reflected upon oppo- 
site sensitized surfaces of a second film in registering positions of the same height 
as the pictures on the first film. Both films are then moved step by step the 
same distance in the same direction for the normal picture height. The second 
film is thus prepared from the two pictures carried by the first film. 

1.802.802. Gyroscopic Scanning Device for Vertical and Horizontal Scanning. 
F. E. BEST. April 28, 1931. Scanning means which includes a high-speed 
rotary reflector having a relatively great gyroscopic action. The apparatus 
while in operation can be moved freely in any plane that does not involve a 
tilting of the axis of rotation of the rapidly rotating part, thereby permitting 
scanning operations in both vertical and horizontal planes. 

1.802.803. Device for Transmitting Vision Electrically. F. E. BEST. 

28, 1931. Television system in which two rotatable disks are each provided 
with a plurality of slots which are adapted to reverse as the disks are rotated 
to progressively permit the passage of contiguous lines of light. One of the 
disks is illuminated in proportion to received electromagnetic impulses in close 


proximity to the slots therein. The operation of a spark gap is observed through 
the slots in the disks. The image of an object is projected onto a photoelectric 
cell in the form of a plurality of contiguous lines of light of varying intensity 
and each line as it is projected on the cell will vary the conductivity of the cell 
thereby varying the electric current that will be transmitted through the cell 
and proportionately varying the strength of illuminating intensity of the spark 
between the electrodes of the receiving apparatus thereby producing in said 
receiving apparatus a line corresponding in intensity to the line of light on the cell. 

1.803.087. Safety Device for Regulating Film Loop and Preventing Fire 
Hazard. T. T. ALLEN AND J. F. ADAMS. Assignors to Sentry Safety Control 
Corporation. April 28, 1931. Automatic control for motion picture projectors 
in which the size of the loop for the feeding of the film is maintained at a pre- 
determined length. Where the film is not uniformly fed under the aperture 
plate by the sprockets which engage the perforations in the sides of the film, the 
loop which is maintained above the aperture plate is either greatly lengthened 
so as to "pile up" or the loop may be diminished until the film is torn or broken. 
A switch is provided including spring terminals and a cam normally adapted to 
force the terminals together. A curved plane is fixed on the shaft and extends 
adjacent on the outside of the loop. There is a finger fixed on the shaft and an 
actuator extending inside the loop and adapted to engage the finger if the film 
loop diminishes excessively. The switch is operated to close a circuit for ob- 
structing the light rays and preventing fire hazard with respect to the film until 
the loop is restored to its normal size. 

1.803.088. Safety Shutter Control and Automatic Change-Over System. 
T. T. ALLEN AND HUMBERT GODOY. Assigned to Sentry Safety Control 
Corporation. April 28, 1931. A shutter mechanism designed to close the aper- 
ture to prevent the projection of the film images; first, where it is desired to change 
the projection from one machine to another; and second, where the projection 
is faulty, caused by the breaking of the motor belt, the blowing of the motor 
fuse, the loss of the film loop, or the breaking of the film. The shutter of one 
projecting machine can be automatically closed and the shutter of an adjacent 
projecting machine opened under electrical control. In case two or more ma- 
chines are used, after being properly focused, the first film reel may be mounted 
in one of the machines and the second film reel in another machine. The mecha- 
nism is designed so that by pressing a button, the projection of the first machine 
will be discontinued and the film of the second or succeeding machine projected 
simultaneously with the stopping of the first machine so that there will be no 
appreciable break in the projection. A pair of solenoids is arranged for operating 
an armature member adjacent to the shutter on each projection machine. A 
switch is provided for alternately energizing one of the solenoids and de-energizing 
the other solenoid to raise or lower the shutter. 

1,803,133. Scanning System for Facsimile Transmission. R. H. RANGER. 
Assigned to Radio Corporation of America. April 28, 1931. A picture repro- 
ducing system for transmitting and receiving picture records, where the picture 
to be transmitted or received is scanned by moving the scanning system longi- 
tudinally of the picture record surface at a plurality of varying speeds. The 
picture surface is carried upon a cylindrical drum and claws are provided for 
gripping the picture surface and holding the same securely upon the drum. 

July, 1931] PATENT ABSTRACTS 143 

The scanning mechanism is operated through a gear shift which controls t he- 
rate of movement of the scanner with respect to the picture. 

1,803,278. High-Frequency Control of a Kerr Cell. T. W. CASE. Assigned 
to Case Research Laboratory, Inc. April 28, 1931. A sound modulating circuit 
is provided for operating upon a high-frequency oscillator and producing tlu-rt-- 
from high-frequency current modulated in accordance with sound vibrations. 
The modulated energy is impressed upon a rectifying circuit and from the recti- 
fying circuit the energy is supplied to a Kerr cell. The Kerr cell varies a beam 
of polarized light in accordance with the modulations impressed upon the carrk-r 
current for the production of a photographic record of light waves corresponding 
to sound waves. The variable light rays thus produced are directed upon a light- 
sensitive film for the recording of sound in accordance with the initial operation 
of the sound pick-up circuit. 

1,803,313. Film Guide for Projectors. CARL BORNMANN. Assigned to Agfa 
Ansco Corporation. May 5, 1931. A film guide for projectors which con- 
sists of a metallic stamping having a rolled, horizontally extending upper edge 
and resilient fingers depending therefrom and adapted to engage the film ad- 
jacent its edges. The resilient fingers bear against the film and maintain the 
edges of the film flat against the film guide during the movement of the film 
past the exposure aperture. 

1,803,346. Electromagnetically Operated Light Gate for Recording Sound 
F. H. OWENS. May 5, 1931. A sound record is recorded on a film by an electro- 
magnetic gate which is operated in accordance with the actuation of a sound 
pick-up circuit for permitting variable light to reach the sensitive film strip. 
The light gate is operated electromagnetically and admits light through a system 
of lenses to the light-sensitive film. The parts of the light gate consist of over- 
lapping plates which are shifted vertically with respect to each other for con- 
trolling the passage of light upon the film strip. 

1.803.403. Sound-on-Film Attachment for Disk Type Phonographs. F. H. 
OWENS. May 5, 1931. An attachment for disk type phonographs in which a 
frame carrying a pair of reels with a film strip reel thereon is adapted to be 
mounted within a phonograph cabinet and the reels driven from the phonograph 
drive shaft. The frame carries a light source and a light-sensitive element 
between which the film having a sound record thereon is moved. The light- 
sensitive element operates a sound reproducing circuit in accordance with the 
sound record on the film. 

1.803.404. Automatic Shutter Mechanism for Controlling Printing Light 
Intensity. F. H. OWENS. May 5, 1931. A shutter mechanism is em- 
ployed in a film printing apparatus, which shutter is controlled in accordance 
with the intensity of the transmitted light of the printer. As the film is moved 
past the shutter opening, the size of the shutter opening is varied in accordance 
with varying light intensities selected for the film. The operating means con- 
sists of a continuous band having undulations or cam faces formed thereon. 
The shutter is mechanically connected to a member which is actuated by the 
movement of the cam faces on the continuous band to open or close the shutter. 
The movement of the film controls the operation of the moving band for control- 
ling the effect thereof upon the shutter for determining the light intensity to 
which the film is subjected. 


1,803,572. Cabinet Assembly for Portable Pictures and Sound Reproducer. 
F. VON MADALER. May 5, 1931. A cabinet assembly for a portable motion 
picture and sound reproducing mechanism wherein a phonograph turntable is 
positively driven by a shaft and a film reeling device slippingly connected to the 
drive shaft. A second film reeling device is adapted to be connected 
to the drive shaft at will. There are film feeding devices disconnectably driven 
by the drive shaft. The mechanism is mounted within a cabinet having a 
horizontally extending shelf carrying a reflecting panel which is utilized for the 
reflection of the reproduced picture on a screen erected above the cabinet structure. 
The driving mechanism operates a ventilating system to maintain the apparatus 
within the cabinet cool during the simultaneous projection of pictures and the 
reproduction of sound from a sound record carried by the film. The apparatus 
is arranged so that the sound record may be reproduced without the accom- 
paniment of the picture. 

1,803,700. Simultaneous Multiple Scanning and Transmission over Separate 
Channels. F. GRAY. Assigned to Bell Telephone Laboratories, Inc. May 5, 
1931. Scanning system for television wherein the scanning disk has apertures 
arranged in the form of a spiral of two convolutions, employed to project two 
beams of light simultaneously upon the field of view so that the field is scanned 
by two spots of light moving over different courses. Each of these beams is 
interrupted or modulated at a distinctive frequency. Light reflected from the 
field of view may be received upon a single photoelectric cell and the resulting 
variations impressed upon frequency selective means for separating the compo- 
nents of different constant frequency. The interrupting or modulating of the 
light beams is accomplished by providing a grating of closely spaced parallel 
rulings over each of the apertures of the scanning disk, the spacing of the lines 
being different for one convolution of the spiral than for the other. Separate 
stationary gratings are provided, one for each convolution of the spiral having, 
respectively, the same spacing of rulings as the apertures of the corresponding 
convolution of the spiral. The gratings are so designed as to have rulings vary- 
ing in opaqueness from the center to the edge to produce variations in the light 
beam in a sinusoidal manner. A large number of beams may be employed and 
any suitable means used to direct and modulate the beams. The image currents 
produced as the result of scanning and comprising a plurality of modulated 
frequency components are separated by means of filters, demodulated, and trans- 
mitted over separate transmission lines, respectively. 

1,804,170. Method of Making Motion Picture Screens. W. H. C. LASSEN. 
May 5, 1931. Screen for talking motion picture systems where a laminated 
screen is provided with perforations uniformly distributed over the surface 
thereof and through which the sound from loud speakers located behind the 
screen may be readily directed. The screen consists of a perforated fabric sheet 
having an adhesive dressing applied over the sheet in a manner to keep the 
perforations open with a layer of glass globules applied to the dressing extending 
into the perforations. The glass globules which extend over the surface of the 
perforated screen provide a reflecting surface for securing finer reproduction 
of the motion picture. 

1,804,208. Manipulating Attachment for Lens Focusing Mechanism of 
Projectors. N. J. NORTHINGTON. May 5, 1931. Lens focusing mechanism 

July, 1931[ PATENT ABSTRACTS 145 

which includes a rack, a pinion, and an upwardly extending pinion shaft pro- 
jecting through the lens housing. There is a worm wheel secured to the end of 
the pinion shaft and a manipulator shaft is provided with a worm thereon mesh- 
ing with the worm on the pinion shaft so that motion may be imparted to the 
lens focusing mechanism from a position remote therefrom and without inter- 
fering with the operation of the motion picture projector. 

1,804,289. Sound Recording and Monitoring System. L. A. TAYLOR. 
May 5, 1931. An apparatus for recording sound and at the same time actuating 
a monitoring circuit for indicating the quality and characteristic of the sound 
being recorded. The recording circuit includes a galvanometer with a mirror 
thereof for laterally focusing a beam of light from a light source in accordance 
with sound waves. The moving beam of light is directed upon a light-sensitive 
film. An optical system is provided for deriving a portion of the vibrated light 
beam and directing the said portion of the light beam upon a light-sensitive cell 
for operating the monitoring circuit. 

1,804,295. Mechanically Resonant Filter for Eliminating 60-Cycle Hum in 
Reproducing Sound. Dow O. WHELAN. May 5, 1931. Circuit for eliminating 
hum of alternating-current supply in the sound reproducer of a sound motion 
picture system, where the hum arises from the alternating-current light source 
used to direct the beam of light through the sound record on the film. The 
incandescent lamp which is used as a light source in a sound motion picture- 
reproducing system is ordinarily energized from the 60-cycle, alternating-current 
power supply used for lighting the theater. While a frequency of 60 cycles is 
too high to produce a visually perceptible flicker there is a variation in the repro- 
duced sound due to the low-frequency characteristic of the light source. By 
this invention a mechanically resonant filter, having an armature tuned for move- 
ment in unison with the frequency of the light source, is provided in circuit with 
the sound reproducing system for eliminating the sound effects produced by the 
alternating current change in the incandescent light source. 

(Abstracts compiled by John B. Brady, Patent Attorney, Washington, D. C.) 



J. I. CRABTREE, Eastman Kodak Co., Rochester, N. Y. 

L C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 


K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 

H. T. COWLING, Eastman Teaching Films, Inc., Rochester, N. Y. 

Board of Governors 

F. C. BADGLEY, Canadian Government Motion Picture Bureau, Ottawa, Canada 
H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Rochester, N. Y. 
J. I. CRABTREE, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
K. C. D. HICKMAN, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 
J. E. JENKINS, Jenkins & Adair, Inc., 3333 Belmont Avenue, Chicago, 111. 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 
W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood Blvd., 

Los Angeles, Calif. 
M. W. PALMER, Paramount Publix Corp., 35-11 35th Ave., Long Island City, 

N. Y. 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

E. I. SPONABLB, 277 Park Ave., New York, N. Y. 










W. V. D. KELLEY, Chairman 


W. C. KUNZMANN, Chairman 

C. L. GREGORY, Chairman 


Membership and Subscription 
H. T. COWLING, Chairman 










O. M. GLUNT, Chairman 


D. McNicoL 


G. E. MATTHEWS, Chairman 










[J. S. M. p. E. 





Projection Practice 
H. RUBIN, Cliairman 



P. A. McGuiRE 


Projection Screens 
S. K. WOLF. Chairman 


Projection Theory 
W. B. RAYTON, Chairman 




W. WHITMORE, Chairman 












H. B. SANTEE, Chairman 


Standards and Nomenclature 
A. C. HARDY, Chairman 


Studio Lighting 
M. W. PALMER, Chairman 





July, 1931] COMMITTEES 149 

Chicago Section 

J. E. JENKINS, Chairman R. P. BURNS, Manager 

R. F. MITCHELL, Sec.-Treas. O. B. DEPUE, Manager 

New York Section 

M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 

Pacific Coast Section 

D. MACKENZIE, Chairman G. MITCHELL, Manager 

E. HUSE, Secretary H. C. SILENT, Manager 

L. E. CLARK, Treasurer 


Burns, Bruce: Born November 24, 1897, at Dayton, Ohio. B.S. Throop 
College of Technology, 1919; B.S. in M.E., California Institute of Technology, 
1920; research, Trumble Mfg. Co., 1920-21; chief engineer, Pneu-shox, 1922-25; 
research, Hughes Tool Co., 1925-28; chief engineer, Hughes Development Co., 
1928-31; technical director, Multicolor, Ltd., Feb., 1931, to date. 

Crabtree, J. L: See January, 1931, issue of JOURNAL. 

Franklin, H. B.: Born April 4, 1889, at New York, N. Y. College of the City 
of New York; theater department, Paramount Famous Lasky Corporation; 
president, Fox West Coast Theaters until 1930; president, Hughes-Franklin 
Theaters, 1930 to date. Author of Motion Picture Theater Management and 
Sound Motion Pictures. 

Golden, N. D.: Born July 4, 1896, at Bellaire, Ohio. Attended Emerson In- 
stitute, Columbia University, Washington College of Law; U. S. Army, 1917-19; 
assistant chief, Motion Picture Division, U. S. Dept. of Commerce, 1926 to date. 

Ives, C. E.: Born February 26, 1902, at Rochester, N. Y. Research Labora- 
tory, Eastman Kodak Company, 1919 to date. 

Miller, A. J.: Born March 24, 1903, at Rochester, N. Y. Research Labora- 
tory, Eastman Kodak Company, 1919 to date. 

North, C. J.: Born September 13, 1892, at Swampscott, Mass. A.B., Harvard 
University, 1914; post-graduate work, Columbia University. Assistant, Bureau 
Branches and Customs, War Trade Board, 1917-18; managing editor, Export 
Trade and Finance, 1919-23; chief, Motion Picture Division, U. S. Dept. of Com- 
merce, 1929 to date. 

Otis, R. M.: Born January 17, 1900, at New Brunswick, N. J. B.S., Cali- 
fornia Institute of Technology, 1920; Ph.D., California Institute of Technology, 
1924; Research Fellow in Physics, California Institute of Technology, 1920-24; 
engineering department, Western Electric Co., 192425; high-voltage vacuum 
tube research and development, Bell Telephone Laboratories, Inc., 1925-27; 
director of research, Hughes Development Co., 1927 to date. 

Scott, E. K.: Born 1868, at South Leeds, England. Graduated Leeds Univ- 
sity. Electrical engineering department, University of Sydney, 1904; lecturer 
at University College, Finsbury Technical College and Northampton Engineer- 
ing College; consulting engineer. 


In the June issue of the JOURNAL, p. 807, the biographical sketch of Mr. A. P. 
Rippenbein was incorrectly presented. The following is the correct version: 

Rippenbein, A. P.: Born 1893, at Elizabeth, N. J. Electrolytic metal de- 
partment, I. G. Farbenindustrie A.-G. 1919-28; general manager, American 
Rocono, Inc., 1930 to date. 



The Spring Meeting of the Society was held in Hollywood, Calif., 
May 25th-29th, with headquarters at the Hotel Roosevelt. The 
technical program consisted of sixty-five technical papers, including 
symposiums on color photography, sound recording, studio practices, 
laboratory practices, and theater practices. In addition to these, 
there was a symposium of four papers dealing with the camera and 
the cameraman. The president turned over the chair during the 
various symposiums to members of the Society who had gained 
distinction in the particular fields as follows : C. E. K. Mees, Director 
of the Kodak Research Laboratories, presided over the symposium on 
color photography; N. H. Slaughter, chief engineer of Warner 
Brothers Studios, presided over the symposium on sound recording; 
and V. B. Sease, director of the Redpath Laboratory of the Du Pont 
Pathe* Film Mfg. Company, presided over that on laboratory prac- 
tices. The final papers program was substantially the same as the 
preliminary program mailed to the membership two months ago. 
Inspection trips were made through the Fox and Paramount West 
Coast Studios, both of which were extremely interesting to the 

The exhibit of motion picture apparatus, held in the gymnasium of 
the American Legion Auditorium in Hollywood, included an ex- 
hibition of apparatus of twenty-four manufacturers, in addition to an 
exhibit arranged by the Historical Committee of the Society. This 
exhibit included replicas of old projectors and cameras, in addition 
to the large collection of clippings of motion picture film illustrating 
various processes. 

On the evening of Monday, May 25th, those attending the Conven- 
tion were entertained by an exhibition of recent films of interest. 
Among these were the picture Tabu, supplied by courtesy of Para- 
mount Publix Corp., and Dancing Sinners, supplied by courtesy of 
Metro-Goldwyn-Mayer Corp., and a comedy reel by Multicolor. 



On the evening of Thursday, May 28th, there was an exhibition of 
representative films from various studios, showing recent advances 
in technic. 

A picture taken thirty-four years ago by Mr. Oscar B. Depue show- 
ing scenes in Europe was projected, in addition to another showing 
Mr. Depue addressing the Convention, and describing the telegra- 
phone which he used for recording conversations in 1907. A repro- 
duction of the record on the steel wire used in the telegraphone was 

Several reels of film were projected through the courtesy of the 
American Society of Cinematographers showing scenic views photo- 
graphed on the new supersensitive film. A demonstration was also 
given of a recording made by the new single ribbon microphone of the 
choir of three hundred voices in the Mormon Temple at Salt Lake 
City. Other films were shown for the purpose of demonstrating noise- 
less recording, re-recording, dubbing, and composite shots made by 
the Dunning and other processes. The demonstration film by the 
Fox Studios showed dissolves of various kinds, and one by Tolhurst 
illustrated results obtained by microscopic photography. 

The Society is indebted to Multicolor, Ltd., Technicolor Motion 
Picture Corp., Fox Film Corp., Columbia Pictures, RKO Radio 
Pictures, Inc., United Artists Corp., and the Dunning Process Co. 
for their kind collaboration. 

The semi-annual banquet of the Society was held on Wednesday, 
May 27th, in the Blossom Room of the Hotel Roosevelt, at which 
more than three hundred persons were present. The opening address 
was made by President Crabtree, who then turned the meeting over 
to Mr. Lawrence Grant, Master of Ceremonies. The speakers in- 
cluded Mr. Frank Woods, Dr. C. E. K. Mees, Mr. Lawrence Grant, 
Dr. Lee de Forest, Mr. Clinton Wunder, Mr. Carey Wilson, Mr. 
Joseph I. Schnitzer, Mr. Sol Wurtzel, Mr. John Arnold, Mr. Alvin 
Wyckoff, Mr. Frank Brandow, Mr. William Garity, Mr. Fred Lally, 
and Mr. Donald Crisp. 

A great deal of credit must be given to the Convention Committee, 
headed by W. C. Kunzmann, and the local Arrangements Committee, 
headed by Peter Mole, for the large amount of work which they con- 
tributed toward making the convention a success. Thanks also are 
due Mrs. Peter Mole and Mrs. Donald MacKenzie for arranging an 
attractive program for the ladies attending the convention. 

On the evening of May 19th, members of the Board of Governors 


were the guests of the Executive Committee of the Technicians' 
Branch of the Academy at a dinner held at the Hotel Roosevelt, at 
which time the fullest cooperation between the Society and the Acad- 
emy was assured. The Society is indebted to the Academy for the 
assistance of Mr. Clinton Wunder and Mr. Lester Cowan in arranging 
some of the details of the Convention. 


At a meeting held in Hollywood at the Hotel Roosevelt, May 24th, 
the Editor-Manager was instructed to notify Associate members of 
the Society that a membership certificate may be secured by sending 
a request to the General Office, accompanied by a remittance of one 
dollar. This request can be made conveniently by returning the 
pink slip enclosed in this issue of the JOURNAL, appropriately filled 

At this meeting, final arrangements for the Convention were com- 
pleted. These included a reduction in the registration fee from $5 to 
$2, making the payment obligatory upon all members of the Society. 
There was some discussion concerning the subscription price of the 
JOURNAL, the acceptance of advertising for the JOURNAL, and reduction 
of dues. A motion was made and passed that a committee be ap- 
pointed "to examine the probable effect on the Society's income of 
reducing the price of the JOURNAL, reducing the annual membership 
dues, taking advertising in the JOURNAL, and to report the relative 
values of advertising, sustaining memberships, and other sources of 
income for augmenting the Society's funds." 


The Board of Governors voted to place the names "New York 
and "Detroit" on the post-card ballot to be mailed to the membership 
shortly for deciding the location of the next convention. The period 
chosen for this meeting was tentatively set for October 19th to 2'Jnd. 


The motion was made and passed that "an award of $100.00 shall 
be made annually, at the Fall Convention of the Society, for the 
most outstanding paper published in the JOURNAL of the Society during 
the preceding calendar year. An appropriate certificate shall ac- 
company the presentation. 


"The Journal Award Committee shall consist of not less than six 
active members of the Society, to be appointed by the President sub- 
ject to ratification by the Board of Governors. The Chairman of the 
Committee shall be named by the President and a two-thirds vote is 
necessary for election to the award. (Proxies are permitted.) 

"The Committee shall be required to make its report to the Board 
of Governors at least one month prior to the Fall Meeting of the 
Society, and the award must be ratified by the Board. A list of five 
papers shall also be recommended for honorable mention by the 
Committee. These rules, together with the titles and authors' names, 
shall be published annually in the JOURNAL of the Society." 


"The Board of Governors may consider annually the award of a 
Progress Medal in recognition of any invention, research, or develop- 
ment, which in the opinion of the Progress Award Committee shall 
have resulted in a significant advance in the development of motion 
picture technology. 

"The Committee shall consist of not less than six active members of 
the Society, to be appointed by the President subject to ratification 
by the Board of Governors. Names of persons deemed worthy of the 
award may be proposed and seconded, in writing, by any two Active 
members of the Society and shall be considered by the Committee 
during the month of June; a written statement of accomplishments 
shall accompany each proposal. 

"Notice of the meeting of the Progress Award Committee must ap- 
pear in the March and April issues of the JOURNAL. All names shall 
reach the Chairman not later than April 20th. 

"A two-thirds vote of the entire Committee shall be required to 
constitute an award of the Progress Medal. Absent members may 
vote in writing. The report of the Committee shall be presented 
to the Board of Governors for ratification at least one month before 
the Fall Meeting of the Society. 

"Recipients of the Progress Medal shall be asked to present their 
portraits to the Society, and, at the discretion of the Committee, the 
recipients may be asked to prepare a paper for publication in the 
JOURNAL of the Society. These regulations, the names of those who 
have received the medal, the year of each award, and a statement of 
the reason for the award shall be published annually in the JOURNAL 
of the Society." 



There is mailed to each newly elected member, upon his first pay- 
ment of dues, a gold membership button which only members of the 
Society are entitled to wear. This button is shown twice actual diam- 
eter in the illustration. The letters are of gold on a white back- 
ground. Replacements of this button may be obtained from the 
General Office of the Society at a charge of $1.00. 


Associate members of the Society may obtain the membership 
certificate illustrated here by forwarding a request for the same to 
the General Office of the Society at 33 W. 42nd St., New York, N. Y., 

Society ^Motion Picture Engineers 

Society of Motion Picture Engineers 

accompanied by a remittance of $1.00. The request may conven- 
iently be made by appropriately filling out the pink slip attached to 
the contents page of this issue of the JOURNAL. 

Cash balance, November 10, 1930 


Entrance fees 

Journal subscriptions, sales, and reprints 


Net receipts 



Committee expenses 
General Office Rent 
General Office Equipment 
Miscellaneous General Office expenses 
Publication expenses 

Net Disbursements 

1930, TO MAR. 31, 1931 


$ 9717.71 




$ 3786.55 








Cash Balance on hand March 31, 1931 
Savings Account 
Current Account 



Accounts receivable 
Accounts payable 

Members' equity, March 31, 1931 

$ 2373.65 

$ 1085.20 1,085.20 


Respectfully submitted, 

H. T. COWLING, Treasurer 




Agfa Ansco Corporation 

Bausch & Lomb Optical Co. 

Bell Telephone Laboratories, Inc. 

Carrier Engineering Corp. 

Case Research Laboratory 

DuPont-Pathe* Film Manufacturing Corp. 

Eastman Kodak Co. 

Electrical Research Products, Inc. 

General Theaters Equipment Co. 

Mole-Richardson, Inc. 

National Carbon Co. 

Paramount Publix Corp. 

RCA Photophone, Inc. 

Technicolor Motion Picture Corp. 


Prior to January, 1930, the Transactions of the Society were published quar- 
terly. A limited number of these Transactions are still available and will be 
sold at the prices listed below. Those who wish to avail themselves of the op- 
portunity of acquiring these back numbers should do so quickly, as the supply 
will soon be exhausted, especially of the earlier numbers. It will be impossible 
to secure them later on as they will not be reprinted. The cost of all the available 
Transactions totals $46.25. 





1917 | I 






1918 7 




1920 } 
1921 {I 





1922 \l 
1923 J6 












Beginning with the January, 1930, issue, the JOURNAL of the Society has been 
issued monthly, in two volumes per year, of six issues each. Back numbers of all 
issues are available at the price of $1.50 each, a complete yearly issue totalling 
$18.00. Single copies of the current issue may be obtained for $1.50 each. 
Orders for back numbers of Transactions and JOURNALS should be placed 
through the General Office of the Society, 33 West 42nd Street. New York, N.Y., 
and should be accompanied by check or money-order. 




Volume XVII AUGUST, 1931 Number 2 



Reversing the Form and Inclination of the Motion Picture 
Theater Floor for Improving Vision BEN SCHLANGER 161 

Straight-Line and Toe Records with the Light- Valve 


A Shutter for Use in Reduction of Ground Noise 


A Simple Cine-Photomicrographic Apparatus 


Characteristics of du Pont Panchromatic Negative Film 

D. R. WHITE 223 

The Handschiegl and Pathechrome Color Processes 

W. V. D. KELLEY 230 

Sound Pictures in the Solution of Solar Eclipse Problems 


Presidential Address 

Committee Activities 


Patent Abstracts 

Book Reviews 



Contributors to This Issue 

Society Announcements 






Associate Editors 

C. E. K. MEES 


Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members, $12.00 per annum; to members, $9.00 per annum, 
included in their annual membership dues; single copies, $1.50. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers or abstracts may be reprinted if credit is given to the Journal of the 
Society of Motion Picture Engineers. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930. at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. 




Summary. Two new forms are presented for a motion picture theater, which 
is considered as a structure intended purely for motion picture exhibition under the 
best conditions. These forms affect the present floors: one is arrived at by reversing 
the slope of the orchestra floor, by raising the position of the screen, and by adjusting 
the seats to the new angle of vision; the other, by changing the horizontal angles of 
the seats in relation to the screen. The balcony pitch is also reduced, thus eco- 
nomically reducing the height of the structure and affording a more comfortable view 
of the screen. The plan adapts itself more readily to the enlarged screen than does the 
present type of theater and allows for improved projection and acoustics. 

It is quite striking that with all the interest displayed during the 
past fifty years in the theater arts, we have concerned ourselves so 
little with the theater itself. This statement is made advisedly, 
fully appreciating the difference in general appearance between what 
today's theater presents and the theater of fifty years ago, and also 
giving due cognizance to the plaster turrets and twinkling stars that 
have become a theater art in themselves during the last decade. 
Our present theater is the circular stadium of the Greeks plus the 
balconied enclosure of the Elizabethans, with the proscenium arch 
as it was added to this structural form. There have been no changes. 
We are still using this form, even for a theater art so radically differ- 
ent from the stage as the motion picture. 

There are, of course, many theaters in which motion picture and 
stage performances are combined. These combinations came into 
rather wide usage about fifteen years ago and are still retained, but 
to a smaller extent than in the period just prior to the introduction 
of the talking picture. 

The theater, as we accepted it with slight change from our prede- 
cessors, was little adapted to the exhibition of the silent motion 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Theater Architect, New York, N. Y. 


162 BEN SCHLANGER [j. s. M. P. E. 

picture. We have come to realize that it is even more poorly suited 
to the presentation of sound film entertainment. And now the 
enlarged screen threatens to render the standard theater form 
obsolete in more points than ever. 

Basically, the essential principles of a good theater form are the 
same for both the stage and screen theater. The difference lies in 
the degree to which, and the method by which, these principles must 
be enforced. All theaters should furnish a clear view of the perform- 
ance, should permit the patron to easily hear and understand the 
sounds of the performance, and provide for him the proper comfort 
and safety. Strangely enough, these basic principles, more inexorable 
than ever in the motion picture theater, have been obscured by those 
of mere decoration. With all other fields of architecture moving 
forward, the motion picture theater, weirdly reacting to its modern 
mechanicalism, has somehow taken on surroundings savoring of orien- 
tal voluptuousness. 

In the motion picture theater, vision must be more delicately 
dealt with than ever, because the screen performance is a thing of 
sheer light. Audibility must be more meticulously cared for, be- 
cause the sounds of the screen are greatly amplified sounds. Per- 
haps we need not insist on more comfort for the movie fan than for 
anyone else, but it may be pointed out that good acoustics and good 
vision contribute to the patron's comfort as much as do well up- 
holstered seats and ample ventilation. 

The theater forms concerned in this paper embrace all three of 
the principles named. More directly, however, they affect vision. 
Good vision depends on the disposition of the sight lines, and the 
physical substance of the motion picture representation requires very 
special consideration of this disposition, while the problem is even 
further extended by the enlarged screen. 

The sight lines, as now fixed in the present type of theater, cause 
the spectator to sit with much bodily discomfort and frequently 
with a distorted view of the screen. On the orchestra floor level, 
the present arrangement requires (except at the extreme rear of a 
deep auditorium) that the spectator tilt his head backward to see the 
upper portions of the screen, the amount of tilt reaching a somewhat 
painful degree. This is due to the fact that the chairs are placed on a 
floor that is sloping downward toward the screen, the level of the 
floor being, in most parts, about even with the bottom of the screen. 
In the balcony, the steep angle makes it necessary for the patron to 

Aug., 1931] 



pitch his body forward in order to view a screen that is at a level 
which is in most cases below that of the greater part of the balcony. 
Study has shown that it is impossible to correct these faults without 
entirely disregarding the present theater forms and creating new ones. 
In endeavoring to correct the faults of the present type of orchestra 
seating, the author has developed a plan in which the slope of the 
orchestra floor is reversed, bringing the high point of the floor nearer 
the screen instead of the low point as is now the case in the present 
type of theater. The screen is raised above the level of the eye line 
of the first row of seats nearest the screen. This plan includes a 



FIG. 1. Longitudinal section of proposed motion picture theaUr. 

systematic tilting of the backs of the chairs on the reversed orchestra 
floor slope (Fig. 1). By tilting the body backward and permitting 
the higher part of the floor in front of the seat to support the feet, 
a natural and comfortable position is assumed which allows UK- 
spectator to obtain a complete view of the screen without having 
to raise his head from its natural position. Seats on the orchestra 
level more remote from the screen require less tilt. Fig. 3 shows 
the system of lessening the tilts of the backs of the chairs. The 
angle of tilt in each case is perpendicular to a line of sight drawn 
from the eye level to a point on the screen about one-third the height 
of the screen, measured from the bottom. It is at this height of the 
screen where most of the action takes place and where the spectator's 



[J. S. M. P. E. 

eye is chiefly focused. The angle formed between the back of the 
chair and the seat is 98 degrees and is kept constant for each and 
every chair. This angle has been found to be most conducive to 
correct and restful posture. Heretofore, only the placing of the seat 
and the screen were taken into consideration in determining sight 
lines, the matter of posture being entirely disregarded. Realizing 
that variously inclined surfaces are used in theater structures, it 
seems almost incredible that more consideration was not given to 
the inclination of the chairs. The reversed slope of the orchestra 
floor permits establishing a definite relation between the inclination 

Upper level. Lower level. 

FIG. 2. Plan views of proposed motion picture theater. 

of the floor and that of the seat. It would be impossible to apply 
this system of tilting to the present slope of the orchestra floor 
because the proper angle of the seat with respect to the back of 
the chair could not be maintained without leaving the feet un- 
supported. Sight lines from the orchestra level cannot, therefore, 
be improved for screen entertainment unless the slope of the orchestra 
floor is reversed. 

While this arrangement distinctly improves the orchestra seating, 
it also serves as a means by which the complete form of the theater 
may be revised to suit the requirements of the screen performance. 
The faults of the present orchestra seating are greatly magnified 

Aug., 1931] 



when the enlarged screen is used because the spectator then has to 
tilt his head backward even further than it is now necessary with the 
small screen. And so the enlarged screen has also served as an im- 
portant agent in determining a new form for the theater structure. 

Reversing the slope of the orchestra floor also brings many decided 
advantages to the balcony, which can now be kept low and of a 
slight pitch, made possible by the low point of the rear of the re- 


FIG. 3. Diagram demonstrating relation between chair tilt and sight lines. 

versed orchestra floor. The balcony thus becomes more desirable 
for two reasons: (1) due to the fact that the level of the screen 
is very much the same as that of the balcony the sight lines are 
greatly improved and, (2) direct and easy access to the balcony from 
the street level is provided, the difference in levels being surprisingly 
small. This is made possible by reducing the pitch of the balcony 
and by placing the rear of the orchestra slightly below the street 
level (Fig. 1). This plan requires only a few steps and a small easy 
ramp from the lobby to the orchestra level. 

166 BEN SCHLANGER [J. S. M. i>. i:. 

Although the requirements of good acoustics and motion picture 
projection might have been secondary considerations in this instance, 
they were by no means disregarded. The shape of the auditorium, 
as developed from this new disposition of sight lines, lends itself to a 
better acoustic form and provides for a smaller angle of projection 
than the shape of the present type of theater. The projector is 
lowered to a level almost even with the top of the screen. 

Besides meeting the requirements of good motion picture exhibition, 
this form of theater is also economical to build. Fig. 1 shows, by 
means of dotted lines, the form of the present type of theater com- 
pared with the new form, the latter being indicated by the heavy 
solid outline. Note the reduction in the height of the entire struc- 
ture, due to the low level of the balcony and the projection booth. 

The theater structure shown in Fig. 1 and Fig. 2 has a seating 
capacity of 1700 seats, the outside dimensions of the structure being 
90 feet in width and 140 feet in length. The average interior height 
is about 36 feet. The screen used for this theater is 22 feet high 
and 36 feet wide. A theater of these dimensions was selected in 
this instance for two reasons: firstly, because the dimensions are 
practically controlled by the requirements for good vision and 
hearing, and secondly, because its seating capacity would be that of 
the average motion picture theater. To design a theater for a 
greater seating capacity it would be advisable to use a somewhat 
larger screen, increase the distance between the first row of seats 
and the screen, increase the distance between the screen and the front 
facia of the balcony, and then to place the additional rows of seats 
at the rear of the orchestra and balcony, respectively. Of course, 
there is a limit as to how far back from the screen seats may be 
placed and yet maintain coordination of vision and hearing. It 
is also inadvisable to make the width of the theater too great for 
the angle of vision necessary for the large screen. Fig. 2 shows 
the maximum angle of vision as 108 degrees in relation to the screen. 
Seats placed outside this angle would afford a distorted view of the 
screen. The smaller screen permits a more obtuse angle of vision, 
which accounts for the fan shape of many existing theaters. A 
smaller theater than the one shown in Fig. 1 and Fig. 2, using a 
large screen, could also be designed according to this new plan by 
reversing the process described for increasing the size. 

Fig. 2 shows the seating arrangement of the orchestra and balcony, 
considering the larger screen. There are here incorporated two 


definite changes from the present type of seating. OIK- is the re- 
versal of the front curve used as a guide outline for the seating block. 
This was necessary because the ends of the curve now in use would 
cause a certain number of seats to be too close to the screen and too 
much to one side. The other change consists of eliminating tlu 
present system of concentric arcs and introducing in its stead a 
system of angles in the side banks. The plans in Fig. 2 show sight 
lines drawn from the center of the screen to about the center of 
several rows of seats. The backs of the seats are made perpen- 
dicular to the sight lines. This allows the spectator to view the 
complete width of the screen without having to twist his body or 
lose the support of the back of the chair. In the present seating 
arrangement the backs of many chairs face in a direction which 
does not afford the spectator a direct view of the enlarged screen 
unless he twists his body away from the back of the chair. Even 
if the present arrangement of concentric arcs were used in a theater 
employing a large screen the spectators would unconsciously face in 
the direction suggested by the sight lines in Fig. 2. 

It might seem from the nature of this paper, that the problems 
thus far presented are of a purely practical nature and that some 
disregard might have been shown for the esthetic and decorative 
considerations of the interior of the theater. This is not the case 
it is necessary to get in behind the turrets, classic columns, and 
archways to see what really exists. These architectural features 
have always so bedecked the theater as to obscure that which was 
functional and expressive of its purpose. Of all the fields of archi- 
tectural endeavor, what branch could so well express itself as the 
motion picture theater an architecture inspired by a mechanism 
which so delicately transmits various degrees of light and sound? 
Why not an architecture for the theater interior that would be 
limited to the treatment of the intensity, placement, and projection 
of light in its various moods? The very art of the theater should 
demand more intangible surroundings than those which are obtained 
by garden walls and other finite unchangeable forms. The larger 
screen will to a great extent determine the treatment of the interior, 
its very size making it an integral part of the auditorium. 

Generally, the form and treatment of the motion picture theater 
depends largely on the progress made by the technicians. Ten 
years ago the presence of a theater architect at a meeting of motion 
picture engineers would have been unlikely. Today the architect 


must come to them to assimilate the many advances which have 
been made and to incorporate them into his creation of a modern 
motion picture theater. Never before in the history of the motion 
picture industry has there been such a need for a common under- 
standing between the technician and the architect. What of all 
this progress which has been made in the science of motion pictures ? 
Where will the results be utilized? Will it all finally resolve into a 
little machine in the home in which will be heard and seen pygmy 
images of people in the midst of dwarfed backgrounds? Or will 
there be an auditorium that is so motivating and complementary to 
a large screen presenting a large panorama of figures against back- 
grounds whose scale in relation to the viewer will be so impressive 
as to make a home television set a toy? 


MR. SEAVIER: Mr. Schlanger's paper leads me to believe that at last the pro- 
jectionist has found a friend, since, as shown in the paper, the balcony, and hence 
the projection room, will be lowered and the angle of projection will be decreased. 
Many millions of dollars have been spent in building very fine theaters, but the 
importance of the angle of projection appears to have been overlooked. The sug- 
gestions made are timely and represent a step in the right direction. The pro- 
jectionist will be enabled to put on a more pleasing show and avoid the distortion 
so prevalent in present-day theaters. There will be no need for employing the 
various means for minimizing and compensating for the picture distortion which 
results from the steep angle of projection. 

MR. PALMER: There appears to be a rather ominous factor in this theater 
design in that the person attending such a theater must necessarily go down- 
stairs for his orchestra seat. If he is required to do this he may gain the impression 
that his seat is located in the basement and he may be reluctant to pay as much 
for the orchestra seat as he is willing to pay at the present time. Such a feature 
may react unfavorably on the box-office receipts. 

MR. SCHLANGER: This theater is so designed that there would be no more than 
two or three steps and a ramp having a slight slope, and one would scarcely be 
conscious of having to descend to the orchestra seat. It is even possible to place 
the rear of the orchestra floor at the street level. However, the slight depression 
of the orchestra is a decided improvement in that it makes the balcony more 
accessible. Such an arrangement would provide a greater number of good seats 
than is now available in the present type of theater, and would thus insure greater 
box-office returns. 

MR. FEAR: One of the first things Mr. Schlanger said was that this theater 
would have a seating capacity of about 1700 seats. That would be a moderately 
small house, and theaters of that size seldom have balconies. The modern trend 
of design is toward the stadium type of construction. Furthermore, I believe 
such a design would be unsatisfactory acoustically. The auditorium of the Mor- 
mon Temple at Salt Lake City is probably one of the most perfect acoustical 


auditoriums ever built, and acoustical engineers are striving to achieve the same 
results in the design of other buildings. 

At the present time the motion picture industry has a five hundred million dollar 
bonded indebtedness, primarily upon new theaters. There are very fev. 
theaters being built at the present time, due not only to this huge indebted 
but due most probably to the fact that there is one seat for every ten persons in 
the United States, and the normal weekly attendance does not fill the hou 
their capacity. In the small theater, with a seating capacity probably under 
2500, the motion picture with sound is the primary attraction. In the majority 
of theaters larger than that, the exhibitors have found it necessary to add stage 
shows. In the type of theater which Mr. Schlanger has described, it would be 
practically impossible to have the "flesh show" which has appeared to be necessary 
in de luxe houses. In fact, even second-rate houses have been putting on "flesh 
shows" in order to stimulate attendance. 

I believe that a house of 1700 seats would never require a large screen. We 
found that when Warner Bros, put in a large size (22 by 40 feet) picture, those sit- 
ting in the first ten rows moved back. If this happened in a de luxe house the 
size of Warner Bros.' theater, I cannot see how such large pictures could be shown 
in a small house. 

MR. SCHLANGER: In the design which I suggested, the screen was placed 
sufficiently far from the first row of seats so that no one would have to 
move further back from the screen. Due to the large screen, a considerable dis- 
tance must be provided between the screen and the first row of seats, and economy 
of ground area must be considered. In order to get the 1700 seats in a minimum 
ground area it is necessary to add the balcony. Such a number of seats cannot be 
arranged in the small space provided unless the type of theater suggested is used. 
A stadium would require a much larger lot. 

I would like to hear expressions of opinion from some of the acoustical engineers 
as to why a form so extremely simple and shaped like a megaphone should not 
be satisfactory acoustically. The disposition of the sight lines brings down the 
cost of the building due to the flatter lines, lower balconies, and lower projection 
booth, all of which tend to decrease the height of the structure and the cubical 
content, or volume, of the auditorium. 

It is true that at the present time stage shows are held in motion pict tin- 
theaters, and there will probably be a need for them for some time to conn , in 
order to promote box-office receipts. But I hope, and believe, that the talking 
motion picture will soon be developed to such an extent that there will no longer 
be a need for "flesh" performances. However, if stage shows are required, an 
orchestra pit can easily be built into the theater as there is plenty of space be- 
tween the front row of seats and the screen. 

MR. SHEA: I recommend that the Sound Committee investigate the acoustical 
problems involved. One of the problems which might be considered is the 
elimination of the pocket under the balcony which appears in so many present 

MR. SCHLANGER: In this theater the ceiling underneath the balcony rises 
upward toward the screen. In present theaters the front of the balcony is the 
low point. At all points in the design an attempt was made to shape the surfaces 

170 BEN SCHLANGER [J. S. M. P. K. 

so they would be acoustically good. The great simplicity of the design will 
tend to provide good acoustical quality. 

The design illustrated in my paper makes it possible to eliminate the fixed pro- 
scenium between the audience and the screen. It would be very advantageous to 
have the form immediately preceding the screen changeable. The setting would 
not have to be of a structural quality having ornamental plaster and supporting 
beams. The proscenium could be arranged in such a manner as to give an effect 
which would best suit the tenor of the picture being shown. 

MR. FEAR: The size of the screen is more or less determined by the size of the 
picture that can be shown without excessive graininess. The distance of the screen 
from the observer determines whether the grain will be noticeable or not. Pri- 
marily the large picture was introduced to improve the view of the screen in large 
houses, the larger house requiring a larger picture. The more remote a spectator 
is from the screen the harder it is for him to see the detail on the small screen. In 
the small house having, say, 1700 seats, no difficulty is encountered in distinguish- 
ing all details of a screen 15 by 20 feet having a height to width ratio of 3 to 4. 
Graininess is a disturbing matter to the audience. The more grain in the picture, 
the greater is the eye-strain, or the greater the concentration required to follow 
the picture. 

MR. SCHLANGER: There are reasons for enlarging the screen other than that 
of clarifying the detail of the picture. These reasons might be considered es- 
thetic, dealing with the treatment of pictorial composition and scale, as well as 
with the problem of widening the action of the picture. 

MR. JONES: I would like to congratulate the author of the paper. Of course, 
it is a radical departure and when anything new is proposed there are always a 
million reasons given as to why it cannot be done. I believe we have been very 
fortunate in having a paper as stimulating and imaginative as this and hope that 
the future will bring something better than we have had in the past. Whether or 
not the design suggested will be the ultimate practical form does not detract from 
the value of the paper, which brings to our attention many of the things which 
can be accomplished. I have expressed myself often to the effect that in the past 
the theater has been built and the optics of the motion picture put into it. This 
is a serious attempt to build a theater around the optics of the motion picture, 
and is something which we will have to think about and analyze. 

MR. DIETERICH: I want to express a great gratification in the application of 
certain well-known optical principles which Mr. Schlanger has shown in his design, 
especially from the point of view of "easing up" the spectator. The question of 
looking with ease at the screen includes also the large screen because the ease 
of looking at something depends on the distance from the object as well as its size. 
That we have to move back in certain theaters when a wide picture is shown re- 
sults from the fact that in looking at an object the strain caused by trying to focus 
the eyes over an angle greater than 30 degrees on each side is very disagreeable 
and even painful. The first row of seats should be placed in such a position and 
at such a distance from the screen as to permit a maximum angle of view of 60 
degrees. If, therefore, a picture 36 feet wide be shown, we should have for the 
first row a minimum distance from the screen of about 36 feet. The inclination 
of the head and body makes it easy to look up at this distance, although a head- 
rest might be considered for such cases. We have about 30 degrees allowable for 


easily viewing a picture up and down, and I believe that the structural prineipl s 
as outlined will help to make it easier to look at the whole screen. This fratim- 
should affect the box-office returns to an advantageous extent. 

MR. SCHLANGER: I have considered the matter of the head-rest and have found 
that the vertical axis of gravity of the body thrown backward to view the pictun- 
would be so located as to obviate the need for a head-rest, even with the greatest 
tilt encountered in the seats nearest the screen, and the bodily posture of the 
viewer would be quite comfortable in viewing the screen from any seat in the 



Summary. A comparison is made of certain types of sound recording by the 
variable density method, assuming a light-modulation device which is itself free 
from distortion. These types are: (1) toe recording where only the toe of the H & D 
curve is used both for negative and for positive; (2) composite straight-line records 
where negative exposures are confined to the straight-line portion of the H & D curve, 
and in printing use is made of a portion of the positive toe, the over-all projected 
gamma being greater than unity; (5) straight-line recording where both negative 
and positive exposures are confined to their respective straight-line portions, and 
the over-all projected gamma equals unity. 

The analysis shows that, by observing certain requirements, distortionless sound 
records can be made on all three types. In signal volume the toe record is louder 
than the composite and the latter louder than the strict straight-line record. In 
ground noise the toe record is inferior to each of the other two. The signal-to-noise 
ratio is greatest for the record where only the straight lines are used and least for the 
toe record. 

The application of noise reduction to these three records is discussed, and it is shown 
that, with the same freedom from distortion, a noise reduction of6db. may be attained 
in toe recording, 10 db. in the composite type, and 14 db. in the third type. 

The fact is emphasized that the pictorial object is not necessarily identical with the 
acoustic, since pictorially useless toe recording is capable of acoustic excellence. 

Sensitometric data are discussed, and it is pointed out that in computing the over-all 
gamma account must be taken of the ratio of negative printing density to negative 
visual diffuse density, and of the ratio of projected print density to visual diffuse 
print density, as well as the distinction between intensity scale and time scale sen- 


In any discussion of processing technic for sound records on photo- 
graphic film, it is essential to keep in mind the distinction between the 
pictorial result desired and the object of sound recording, in order 
that preconceptions based on pictorial technic shall not be improperly 
transferred to the technic of sound reproduction. 

It is the object of pictorial presentation to reproduce for the eye 

* Presented in the Symposium on Laboratory Practices at the Spring, 1931, 
Meeting at Hollywood, Calif. 

** Electrical Research Products, Inc., New York, N. Y. 


a wide range between highlights and shadows, together with accept- 
able gradations of the intermediate values of the scene photographed. 
The object of the sound film technic is to produce a positive trans- 
parency in which the projected transmission from point to point along 
the length of the film shall be proportional to the exposure of the nega- 
tive at the corresponding point. This statement is applicable to the 
variable width as well as to the variable density track, provided we 
understand by "transmission" the light reaching the photoelectric cell 
from a given position of the scanning line on the sound track divided 
by the light from the scanning line direct. In the present discussion 
consideration is given exclusively to the variable density type of 
sound record and to the processing technics which have been pro- 

The requirements of pictorial reproduction have been thoroughly 
discussed by L. A. Jones, 1 who shows that faithful reproduction of 
brightness values is attained only when the over-all gamma is unity, 
with the further restriction that negative exposure and positive print- 
ing shall be confined to the straight-line portions of the respective 
H & D curves. In practice it is common to use an over-all gamma 
greater than unity and allow the positive print to intrude into the 
toe of the positive curve, for reasons depending on lens performance 
and conditions of screen illumination. 

The requirement that the over-all gamma shall be unity and the 
positive and negative exposures shall be confined to the respective 
straight lines, forms the basis of the classical recommendations for 
variable density sound records where a light source is available which 
can give the desired negative exposure. Another processing technic 
for variable density sound records is based upon a suggestion by 
F. F. Renwick. 2 This involves toe exposure of the negative, develop- 
ing the negative to a high gamma and printing it on a positive material 
similar to the negative material, using the positive toe and developing 
the print to the same high gamma as the negative. Such a procedure 
makes it possible to use positive emulsion with sources of restricted 
intensity and has been recommended even for the unrestricted light 

Both of these processing methods are in practical use today, and it 
is the purpose of this paper to investigate the results obtained in the 
reproduction of sound by the two methods, incidentally establishing 
the sensitometric foundation more precisely than was possible some 
years ago. 

174 DONALD MACKENZIE [j. s. M. p. E. 

It will be assumed that we have a light source capable of being 
modulated by electric currents so that the wave of light variation 
shall be a distortionless copy of the current wave modulating the light 
source. For the sake of definiteness in the discussion, we shall limit 
ourselves to the case where the light intensity is constant and the 
time of exposure varied by the current, although it will later be 
pointed out that the conclusions reached apply as well to the case of 
constant time of exposure and varied light intensity. 

The two processing technics to be examined are popularly known 
as straight-line recording and toe recording, and it will be shown in 
this paper that excellent sound records can be obtained from each, 
provided certain requirements are met. 


In any processing where uniformity of results is desired, sensito- 
metric control of development of both positive and negative is neces- 
sary, whatever the type of sound record. The same control is 
necessary for uniformity of pictorial results, although in this case the 
trained eye has been used as a measuring instrument with fair suc- 
cess. For the sound record more impersonal measurements are re- 
quired. Let us examine the sensitometric scales and the kinds of 
measurements involved. 

Sensitometers are classified as time scale or intensity scale. In the 
time scale sensitometer the sensitometric strip is made by exposing 
successive areas of the film to successively increasing intervals of time. 
In the intensity scale sensitometer the successive areas of the strip are 
exposed for a constant time to increasing intensities of light. This 
light variation is accomplished by interposing betweeathe light source 
and the film to be exposed a variable mechanical shutter or a step 
tablet of varying density. 

The sensitometer scales which we take into account in film process- 
ing must be carefully distinguished as to the class in which they belong 
and the kind of light source used in the sensitometer. Further- 
more, the kind of density measurements to be made on the developed 
sensitometer strip must be specified. 

We have to distinguish the following types of sensitometric ex- 

(1) The daylight time scale of the Eastman Kodak sensitometer. This 
instrument uses as a light source the acetylene flame screened to daylight quality, 
and the sensitometer strip is exposed to a constant light of rather low intensity 


for intervals of time which become minutes at the maximum exposure. The 
exposure times increase in square-root-of-2 steps. 

(2) The light-valve time scale of the Western Electric recording machine 
which exposes the negative to a light intensity of 100,000 meter-candles or mon for 
times varying from 1/20,000 to 1/200,000 second. This recording machine 
uses a tungsten light source having a color temperature of about 2800 K. 

(3) The intensity scale represented by the flashing lamps, where the time of 
exposure is about 1/20,000 of a second and the light intensity varies up and 
down from 10,000 or 15,000 meter-candles. The specifications of light quality 
cannot be stated generally. This scale is not involved in the present discussion. 

(4) The intensity scale of the printer, where the light source is usually a 60- 
watt tungsten lamp and the positive film is exposed through the negative. The 
time of exposure is about 1/40 second and the intensity of light transmitted by 
the negative varies from a few score to a few hundred meter-candles. 

The relations between the gammas derived from exposures on the 
above scales involve the failure of the reciprocity law and the de- 
pendence of gamma on the color of the exposing light. It is known, 
for example, that blue light gradations yield a lower gamma than 
gradations of yellow light and we may expect that, apart from failure 
of the reciprocity law, the daylight time scale gamma will be lower 
than the tungsten time scale gamma for the same development. The 
relation of printer intensity scale gamma to daylight time scale gamma 
will involve the color difference between tungsten and daylight as 
well as the difference between time scale and intensity scale exposures 
and the difference in source intensities. 

Experiment has shown that for positive film in a given developer, 
the H & D curve for a definite gamma has the same shape at the toe, 
straight line, and shoulder, whether obtained by time scale or inten- 
sity scale exposure.* It has also been shown experimentally that 
for a given development time in the same developer the following 
ratios exist between the daylight time scale of the Eastman sensitom- 
eter and the light-valve time scale of the Western Electric recording 
machine, and between the Eastman scale and the tungsten intensity 
scale of the printer: 

If the Eastman daylight time scale gamma = 1.00, then 

(1) the light-valve tungsten time scale gamma = 1 .05 

(2) the printer tungsten intensity scale gamma =0.95 

(3) the Cinex (tungsten time scale) gamma = 1 . 05 

These ratios are derived from data collected for the purpose from 

* We exclude from consideration sensitometers using extremely low intensities 

of illumination. 

176 DONALD MACKENZIE [j. s. M. P. E. 

most of the Hollywood laboratories that process variable density 
sound film. The values in the table apply to a wide range of positive 
and negative gammas. 

The intensity gradations of the printer scale are understood to be 
gradations of effective printing densities of the negative printed. The 
significance of this specification will be made clear in what follows. 

H & D curves are customarily plotted with visual* densities as 
ordinates against logarithms of exposure as abscissas. Exposures are 
given in meter-candle-seconds, and densities are measured visually 
by the polarization photometer head (or equivalent) with diffuse 
illumination of the film area being measured. In the Bell & Howell 
back-shutter printer, the light source sends light to the negative 
through two apertures in a line, and so the illumination is to some ex- 
tent specular. Moreover, unless the negative being printed is neutral 
in spectral transmission, its density as appreciated by the positive 
emulsion will differ from its visual density by reason of the difference 
in spectral response of the film and the eye. The ratio of printing 
density to visual density will depend upon the spectral selectivity of 
the photographic deposit, and this ratio will combine with the specu- 
larity of the printing light to yield a printing coefficient for the nega- 
tive which includes the color coefficient as ordinarily understood and 
the geometry of the printing operation. The printing coefficient 
may be equal to, less than, or greater than unity.*" 

Filters introduced in printing the sound negative alter the quality 
of light falling on the negative. This may affect the negative printing 
coefficient at the same time that the color change affects the gamma 
to which the positive is developed. The two effects may be opposed: 
one case was found where they cancelled each other, and the filter 
served merely to reduce the light as would a neutral gray. 

Replacing the 60-watt tungsten lamp by a 200-watt, gas-filled lamp 
and suitable filter has been tried by one laboratory in Hollywood. 
The effect was a 12 per cent reduction in over-all gamma in addition 
to a reduction in exposure. 


The accompanying figures will illustrate the foregoing. Fig. 1 is 
an H & D curve on Eastman positive emulsion, obtained with the 
Eastman time scale sensitometer, and developed in a sound negative 

* "Visual" means in every case "visual diffuse." 
** For determination of color coefficient see reference No. 3. 

Aug., 1931] 



bath to a gamma of 0.50. Visual diffuse densities are plotted against 
log meter-candle-seconds. The same development would be expi 
to give a gamma of 0.53 for light-valve exposures, where visual diffuse 
densities would be plotted against log valve spacings. A slightly 
shorter development would give a light-valve gamma of 0.50 and, as 
stated above, the resulting curve would register with the curve of 
Fig. 1. 

Values of printing coefficient ranging from 1.0 to 1.4 have been 
found. The printing coefficient is the ratio of gradations of effective 
printing densities to gradations of visual diffuse densities of the nega- 
tive. Admitting the possibility of reflections from the negative in 

H & D CURVE T = 0.50 









- --' 


-0.8 -0.4 OX) Q4 OB 1.2 LA 


FIG. 1. Sound negative development. 

the printer which differ from those occurring in the visual diffuse 
densitometer, we can write: 

Effective printing density = A + (visual density X P.C.) 

The effect of the constant A is a shift parallel to the density axis with- 
out change of shape, and thus is equivalent to a change in light inten- 
sity in the printer lamp. The P.C. for the sound negative bath which 
produced Fig. 1 was 1.2; the effecting printing gamma then was 0.60. 
Fig. 2 exhibits the H & D curve of gamma 2.0; it is an Eastman 
time scale strip developed at the Fox Laboratory in Hollywood in the 
positive bath which serves for the sound negative and for the Movie- 



[J. S. M. P. E. 

tone print. The printing coefficient of the negative was found to be 
1.2. The method of determining P.C. is described in connection with 
the next figure. 

Fig. 3 is a plot of print visual density vs. negative visual density in 
the Fox processing. A negative sensitometer strip, the visual densi- 
ties of which were carefully measured, was spliced into a loop of clear 
film and printed at printer points 3, 6, 9, 12, 15, and 18. Prints 
made with the 60-watt lamp with no filter at points 6, 12, and 18 are 
represented in Fig. 3. Similar prints obtained with No. 39 filter and 
a ground glass gave curves of the same shape. The net effect of the 
filter and ground glass is to reduce the light; the change in printing 



H & D CURVE r 2.0 




8 2 g 15 I 







2 -0.8 -OA 0.0 QA 08 

FIG. 2. Composite print development. 

coefficient due to the filter is offset by the reduction in print gamma 
due to the change in light quality. 

Unless there is a variation in gamma with printer point, the shift of 
printer point is equivalent merely to shifting the range of negative 
densities to cover successive (and overlapping) portions of the whole 
printer curve. To obtain Fig. 3, the print visual density was plotted 
against the negative visual density for each printer point separately, 
and the plots were brought into register by appropriate shifting 
along the axis of negative visual density. Fig. 3 gives no indication 
of a variation in gamma with printer point; this result has been 
confirmed on every printer so far examined, provided accurate 

Aug., 1931] 



density measurements are made on the negative loop and on the 
positive prints. 

Study of Fig. 3 shows that a change of 3 printer points is equi /alent 
to a shift of 0.10 along the axis of negative visual density. This is 
confirmed by all the prints made of this negative: the print at point 
6 registers with that at point 18 when shifted 0.40 in visual density. 
It is known from illumination measurements at the printing gate of 
the Bell & Howell back-shutter printer that between points 3 and 18 
there is a linear logarithmic relation between printer point and meter- 
candles at the gate; a change of 12 printer points means a change of 
0.48 in log meter-candles. A change in visual density of 0.40, there- 




r ta 

























DO 0.4 0.8 1.2 1.6 2O 24 


FIG. 3. Apparent printer characteristic. 

fore, is equivalent to a change of 0.48 in log effective exposure; the 
printing coefficient of this negative then is 1.2. 

While this determination lacks precision both in the illumination 
measurements and in the registrations of the different print curves, 
it checks closely with the relation previously stated between the day- 
light time scale gamma and the printer intensity scale gamma. It 
will be recognized that a curve plotted between print visual density 
and negative visual density will give an apparent printer gamma 
higher than the true, if the P. C. of the negative is greater than unity. 
The gradations of negative density should be multiplied by the nega- 
tive P. C. to obtain the true gradations of effective exposure on the 



[J. S. M. P. E. 

positive material. When this is done the true printer gamma is seen 
to be less than the apparent in the ratio of the P. C. 

If the daylight time scale gamma is y T , then the true printer 
















- __ 

0.4 O.8 12 1.6 2.0 24 



FIG. 4. Negative printing coefficient = 1.14. 

1 6 













O4 1.2 


20 24 


FIG. 5. Negative printing coefficient = 1.00. 

gamma is 0.9577-, and the apparent printer gamma (print visual 
density vs. negative visual density) is Q.95y T X neg. P. C. From 
the data shown in Fig. 3, the P. C. is 1.21. 


The relation just stated between printer intensity scale and East- 
man time scale gammas serves to reconcile the results of printer stud- 
ies at five laboratories in Hollywood. These laboratories use differ- 
ent formulas for the sound negative developer. Four of them use 
the Bell & Howell back-shutter printer with no modification of print- 
ing apertures. The negative printing coefficients thus differ from 
one laboratory to another, and curves from two of these laboratories 
(referred to as "A" and "B") are shown in Fig. 4 and Fig. 5. 

Fig. 4 is a curve obtained in the same way as Fig. 3 by consolidating 
the individual curves at separate printer points. The sound negative 
printed in this series of measurements had a printing coefficient of 
1.14. The curve of Fig. 5 is similarly obtained from studies in labora- 
tory "B," where the sound negative had a faint magenta color and 
its printing coefficient was 1.0. This value is indicated both by the 
registrations of separate print curves and by taking into account the 
ratio 0.90 between the Cinex time scale gamma and the printer inten- 
sity scale gamma. 

The positive formula at laboratory "A" was at this time the same 
as at laboratory "B" except that a small amount of citric acid was 
present in one of them. Since the printers are the same, and the 
positive prints were developed in the same type of developer to the 
same contrast as read by the sensitometers (taking into account the 
ratio of the sensitometer scales at the two laboratories) we should 
expect that the true printer curves, each corrected for negative print- 
ing coefficient, would be identical in shape and would register on each 
other. The shift along the axis of negative printing density required 
to effect this registration is due to the difference between the arbitrary 
zeros of Fig. 4 and Fig. 5. The agreement between the two curves 
when so treated is shown in Fig. 6. Here one set of points is the 
curve of Fig. 5, requiring no correction for printing coefficient. The 
other set is taken from the curve of Fig. 4, the corresponding negative 
visual gradations having been multiplied by 1.14, the negative print- 
ing coefficient at laboratory "A." 

We may then take the curve of Fig. 6 to be the true printer curve 
for this positive formula and for the standard printer when the Cinex 
time scale gamma is 2.08. The ordinates of the curve are print visual 
densities. The abscissas are negative printing gradations. Tl 
fore, if it is desired to construct the apparent printer curve in this de- 
veloper at this time of development for any other negative printing 
coefficient than unity, the abscissas of Fig. 6 need only be divided by 



[J. S. M. P. E. 

the negative printing coefficient under consideration. The develop- 
ment to a positive contrast of 2. OS by Cinex or 1.98 by daylight time 
scale is one which is commonly used for picture prints and, therefore, 
also for the sound print of the composite film.* It will be noticed 
that this value of daylight time scale gamma differs by only 1 per 
cent from the Fox positive processing represented in Fig. 2. Errors 
no greater than 1 per cent can scarcely be avoided and it is safe to 
say that the curves of Figs. 2, 4, and 5 belong to the same developed 
contrast. Besides this, the shapes of the toes of the three curves, 

















0/4 0.8 1.2 1.6 2.0 2.4 


FIG. 6. True printer characteristic. 

when printing coefficients are eliminated, are found to be substantially 

A common value of the negative printing coefficient is 1 .2. Equally 
common is the positive contrast of 2.0 by the daylight time scale. 
Having now the true printer curve for this daylight time scale positive 
gamma, we can construct an apparent printer curve between print 
visual densities and negative visual densities which will be representa- 
tive of the processing of Fig. 2, and of the results at laboratories "A" 
and "B" of printing a negative whose printing coefficient is 1.2. 

* In Hollywood studios there is a recent tendency to lower print gammas. 



At this point it is appropriate to introduce the relation between 
projected print density in the reproducing sound head and visual 
print density measured on the densitometer. Data relating pro- 
jected and visual densities of various samples have been collected at 
numerous times, and it has been usually found that the ratio 
of projected to visual density is not a constant but increases at the 
lower values of density. 

This matter is discussed by Tuttle and McFarlane, 4 who tabu- 
late values of visual diffuse density and of reproducer density for 
positive film. In their work the reproducer density was measured 
by a galvanometer in series with the potassium cell. Similar measure- 
ments of densities were made at the Fox laboratories in the course of 
the present work. In Fig. 7 are shown plots of the data obtained in 
these measurements and of the data tabulated by Tuttle and Mc- 
Farlane. It will be observed that to the points in both plots straight 
lines of the same slope can be fitted, intersecting the axis of projected 
density at a point to the right of the origin. The data are represented 
by the equation: 

Projected print density = K -f- (1.22 X visual print density) 

where K has the values 0.03 and 0.04, respectively, for the Fox data 
and for the Tuttle and McFarlane data. 

The existence of this constant K may be attributed to reflection of 
light at the burnished surface of the print. Similar measurements on 
specimen photographic densities not burnished show a straight line 
passing nearly through the origin, the value of K being 0.01 and the 
slope 1.25. These specimens were obtained from the Eastman Kodak 
Company in Rochester and were developed according to their own 

The reflection of light from the emulsion surface in the sound head is 
undoubtedly different from the reflection in the visual densitonu u r 
where the emulsion lies just above a diffusing surface. The plots of 
Fig. 7 indicate reflections of 7 and 9 per cent, respectively, if the con- 
stant K is identified with this effect. 

The existence of an additive constant in projected density implies 
merely a displacement along the axis of projected print density and 
involves no change in shape of the curve. This additive constant 
becomes a multiplying constant when projected transmissions are 
taken instead of projected densities and so is equivalent to a slight 



[J. S. M. P. E. 

reduction in the light from the reproducing lamp. It is, therefore, 
justifiable to multiply print visual densities by a constant to obtain 
projected print densities. This constant, hereinafter called the "pro- 
jection factor," involves the specularity of the reproducing illumina- 
tion and the difference in spectral response between the photoelectric 
cell and the eye. The projection factor thus is allied to the nega- 
tive printing coefficient. 

It is known that projected densities for the potassium cell are some- 
what lower than for the caesium cell. In a particular case investi- 


DPROJ. 1.22 x Dvix + o.03 [A] 
DPROJ. si.22 DV.O. o.04 [B] 





















0.4 0.8 1.2 I.6[TUTTLE 4 MC FARLANE J.S.M.P.E. I5.3-P.35O] 
[FOX DENSITCS] OX) 0.4 0.8 1.2 1. 


FIG. 7. Projection factors. 

gated some time ago, the reproducer densities using the Western 
Electric potassium cell were 6 per cent less than when using the 
Western Electric caesium cell. A convenient compromise, nearly 
correct for both potassium and caesium cells, is obtained by taking 
1.25 as the ratio of projected to visual gamma. On this basis it is 
possible to construct a curve based on Fig. 6, multiplying the print 
visual densities by 1.25 and dividing the negative printing densities 
by 1.2. The resulting curve is the projection characteristic of prints 
from a negative having a printing coefficient equal to 1.2, the print 
development being carried to a daylight time scale gamma of 2.0. 



In Fig. 8 a graphical construction adapted to the use of the data 
which have been presented shows the photographic characteristic 
of toe recording. In the lower right-hand quadrant of this ngun is 
replotted the curve of Fig. 2. In the upper left-hand quadrant is 
plotted from Fig. 6 the curve of projected print densities vs. grada- 
tions of visual negative density, using the projection factor 1.25 and 






PRNTER FONTS 0-2 = A : 0-4 

FIG. 8. Toe recording construction. 

the printing coefficient 1.2. Choosing any point on the negative 
H & D curve and the projected print density to which this point shall 
be printed, we determine the construction by drawing a horizontal 
line through the chosen negative density in the two lower quadrants 
and a vertical line in the upper and lower left-hand quadrants through 
the print curve at the chosen projected print density. Through the 
intersection of these lines in the lower left-hand quadrant a straight 
line at 45 degrees is drawn to represent the printer point. A vertical 

186 DONALD MACKENZIE [J. s. M. p. E. 

line through the chosen point on the negative curve intersects a hori- 
zontal line through the chosen positive projected density and locates 
a point of the over-all curve in the upper right-hand quadrant. 

The oblique line in the lower left-hand quadrant serves to transfer 
the negative densities to the scale of negative visual gradations on the 
horizontal axis at the left. The location of this line determines the 
portion of the positive projected density curve which shall be covered 
by the range of negative densities of the sound record. Remembering 
that the printing coefficient of the negative is 1.2 and that a difference 
in negative visual density of 0.10 is equivalent to a change of 3 printer 
points, we can locate 45 degree lines in the lower left-hand quadrant 
corresponding to any desired number of printer points above or below 
the line we start with. For the sake of illustration, four such printer 
point lines are drawn in Fig. 8 at intervals of 2 printer points. The 
dashed horizontal lines in the two lower quadrants determine the 
negative exposures which will be printed to the same projected print 
density by the appropriate printer lines. For each printer point the 
rest of the construction follows immediately giving the over-all photo- 
graphic characteristics 0, A, B, and C of the upper right-hand quad- 

The printer curve of the upper left-hand quadrant is reversed 
left and right from the usual plotting of such data in order to show 
more clearly the effect of the positive toe. All four of the over-all 
curves terminate to the left in horizontal lines which show the effect 
of printing the negative fog density, and on the right they terminate 
in a horizontal line, the same for all four curves because of the 
positive fog. Photographically considered, these curves are by no 
means suited for pictorial reproduction in as much as the range 
between highlights and shadows is limited and the range of negative 
exposures which show gradation in the final print is narrow. The 
processing represented by Fig. 8, therefore, gives a poor picture. 
How well it serves for sound reproduction cannot be clearly seen 
from this plot, and we require a plot of projected print transmission 
vs. negative exposure. 

In Fig. 9 the four over-all curves of Fig. 8 are replotted in arith- 
metical terms. It will be seen that in each of the four curves of Fig. 9 
there is a region where the curve is nearly straight. Heavy dots 
indicate the limits of approximately linear reproduction and the 
proper average transmission. It must be recognized that the curve 
is nowhere ideally straight but is S-shaped, with a point of inflection, 

Aug., 1931] 



on each side of which the departure from a straight line is small 
enough to be ignored within a certain range of negative exposure. 
The object of sound-record processing is to select a negative exposure 
and a printer point such that the departure from linearity shall be 
small and symmetrical on both sides of the exposure selected, when- 
ever strict linearity is not attainable. 

Printer point C (Fig. 9) clearly shows an approximately straight 
portion much shorter than printer points 0, A, and B. The straight- 
line portions for 0, A, and B are of approximately the same length, UK- 
centers being at nearly the same projected print transmission, but 







(D.-VISUAL DIFFUSE - 0.30 TO 0.46) 

0.2 0.4 *0j6 08 


FIG. 9. Toe record positive. 

corresponding to different values of unmodulated negative exposure. 
A print at 2 printer points above would no doubt be equally success- 
ful, but a print 2 points darker still would undoubtedly show limita- 
tions as great as those of C. 

The curves definitely suggest that equally good results are to be ex- 
pected from unmodulated negative exposures between 0.30 and 
meter-candle-seconds, provided the printer points are so chosen that 
the projected positive transmission shall be the same for all these nega- 
tivesnamely, about 42 per cent, corresponding to a visual print 
density of 0.30, visual transmission 50 per cent. For negative ex- 

188 DONALD MACKENZIE [j. s. M. p. E. 

posures within these limits of permissible variation the modulation 
of the sound record should be restricted to 40 or 50 per cent, in order 
that the maximum and minimum negative exposures shall not sensibly 
encroach on the definitely curved upper and lower ends of the over-all 
curves. Within this range in the choice of negative unmodulated 
exposure, restricting the modulation as indicated, and choosing the 
printer point for a projected positive transmission of 42 per cent, we 
obtain prints of substantially equal volume. The amplitude of 
photoelectric cell current is determined by the swing in transmission 
corresponding to the swing in negative exposure, and it is seen that 
in curves 0, A, and B the swing in transmission is about 44 per cent. 

The proponents of toe recording for sound records have usually ad- 
vocated a negative visual transmission of 50 per cent, printed to a 
positive visual transmission of 50 per cent, with negative and positive 
gammas as in Fig. 8. It appears from the preceding discussion that 
the unmodulated negative transmission is not limited to this value 
although the appropriate printer point yields the same positive trans- 
mission for each negative unmodulated exposure within the per- 
missible range. 

Based on the above conclusions, a toe record on Eastman positive 
film was made with the light-valve, setting the recording lamp to 
result in an unmodulated track density of 0.30 visual diffuse when the 
negative is developed to a daylight time scale gamma of 2.O.* Fol- 
lowing the usual recommendations for toe records this was printed to 
a positive track density of 0.30 visual diffuse, the print being devel- 
oped as had been the negative. These requirements were exactly 
met at the Fox Laboratory. 

A daylight time scale exposure on the negative was printed through 
on the positive. The printed-through densities were measured and 
converted to projected densities by the projection factor, 1.25. This 
over-all curve in terms of projected print density vs. log negative 
exposure in meter-candle-seconds was translated into projected 
print transmissions vs. negative exposures and the open circles in 
Fig. 9 show how closely the actual result agreed with the expected. 
Perfect agreement would locate the circles on the curve in Fig. 9 at 
printer point B. This check appears satisfactorily to vindicate the 
construction employed and the considerations on which it is founded. 
The record showed excellent quality for both speech and music. 

* The light-valve gamma would be a little higher than the daylight gamma, 
but the shapes of the toes would not differ appreciably. 

Aug., 1931] 



Limitations of toe recording remain to be discussed, but the em- 
phasis at this point is upon the fact that, by properly choosing the 
negative exposure, negative modulation, and printer point, a proc- 
essing which is pictorially useless gives a result which is acoustically 

A claim made for toe recording is that the sound negative, when pro- 
jected, is of as good quality as the print to be made from it. In Fig. 10 
the negative curve in the lower right-hand quadrant of Fig. -^ 
is replotted (taking account of the projection factor) in terms of pro- 




I S * 





8 5 






" 02 0.4 06 Ofl ID 


FIG. 10. Toe record negative. 

jected negative transmission vs. negative exposure. No part of this 
curve is straight. 

The foregoing discussion of toe recording has made use of H & I 
curves derived from time scale exposures, whereas the flashing-lamp 
records give intensity scale variations of exposure on the negative. 
In the region of the negative characteristic to which the toe exposures 
are confined, the difference in shape for the same development between 
intensity scale and time scale exposures is so small as to be negligible 
and the conclusions stated above apply substantially to either type 
of negative modulation.* 

* In the Fox development, daylight time scale strips at gammas of 1.81 and 
2.15 show toes which do not differ in shape below a visual density of fl 

190 DONALD MACKENZIE [j. s. M. p. E. 


Before studies were made of the negative printing coefficient, pro- 
jection factor, and relations between sensitometric scales, the curves 
of Fig. 1 and Fig. 2, where the negative gamma is 0.50 and the positive 
2.0, would have appeared to define a sound record processing in con- 
formity with the classical specification of an over- all gamma of unity. 
As a matter of fact, such processing can be used successfully for the 
reason that the positive development represented by Fig. 2 is suitable 
for the picture prints, and a development corresponding to Fig. 1 can 
be readily provided for the sound negative on positive emulsion. 

Taking into account the projection factor, the negative printing 
coefficient, and the relation of true printer gamma to sensitometer 
gamma, we can enumerate the factors which enter into the determina- 
tion of the over-all projected gamma. They are as follows: 

(1) the light- valve gamma, derived from the curve plotted between negative 
visual density and log light- valve spacing ; 

(2) the apparent printer gamma, derived from a plot of print visual density 
vs. negative visual density; 

(3) the projection factor, depending somewhat on the type of cell and the 
structure of the sound head. This factor has been taken as 1.25 for reasons given 

The over-all gamma is the product of the light-valve gamma times 
the apparent print gamma times the projection factor. It is this 
triple product which should be unity in order strictly to conform 
to classical requirements. The apparent printer gamma must be 
determined by making prints of the actual negatives for which the 
light- valve gamma is derived. The three factors whose product is 
formed may be written thus: 

. (1). (2) 

visual negative density print visual density 

/N. 7* * ~. /\ 

log valve spacing negative visual density 

print projected density print projected density 

= - - = over-all gamma 

print visual density log valve spacing 

It is customary to control the processing by the use of suitable 
sensitometer exposures developed along with sound negatives and 

not likely that the flashing-lamp gammas would differ more than 10 per cent from 
the daylight time scale gamma, and it has been mentioned that an intensity 
scale curve coincides with a daylight time scale curve of the same gamma. There 
remains the chance that a different negative exposure would be required to give 
the desired negative density. 


sound prints. If, for example, the daylight time scale sensitometer 
is used to expose the sensitometer strips, we have the following 
relations between sensitometer gammas and the factors listed above: 

(1) Light- valve gamma = 1.05 X daylight time scale negative gamma 

(2) Apparent printer gamma = 0.95 X daylight time scale positive gamma 

X negative printing coefficient 
= true printer gamma X P.C. 

(3) Projection factor =- 1 . 25 

If a Cinex tungsten time scale sensitometer is used to make the 
control strips, it should be remembered that the Cinex gamma is : 
per cent greater than the daylight time scale gamma and 10 per cent 
greater than the true printer gamma. Concisely stated, the over-all 
gamma equals 1.25 X product of positive and negative daylight 
time scale gammas X negative printing coefficient, or 1.12 X product 
of Cinex negative and positive gammas and negative printing coeffi- 

The sound negative bath which gave a daylight time scale gamma of 
0.50, the curve of Fig. 1, would have given this same curve for Cinex 
exposures had the development of the Cinex strips been a little shorter. 
The equality of Cinex gammas and light- valve gammas permits us to 
use the curve of Fig. 1 as representing the light-valve gamma of 
0.50. The bath from which the curve of Fig. 1 was obtained produced 
sound negatives with a printing coefficient of 1.2. The curve of pro- 
jected print density vs. negative visual density, shown in the upper 
left-hand quadrant of Fig. 8, describes sound positive processing 
to a Cinex gamma of 2.08, of prints made from a negative of printing 
coefficient 1.2. From what has been said just above, the over-all 
projected gamma, instead of being unity, is 1.4. 

It has been the practice to set the recording lamp to obtain an ex- 
posure on the sound negative equal to 10 times the exposure at which 
the negative H & D curve begins to be straight. For Eastman posi- 
tive emulsion in the usual sound negative bath, the visual density at 
which the H & D curve becomes straight, is about 0.35 or 0.40 X 
gamma for values of gamma between 0.3 and 0.7. 

It is seen from Fig. 1 that the density at the toe exposure is 0.120. 
The density for the unmodulated negative track which the standard 
recommendation calls for is then 0.70 visual diffuse (corresponding to 
a visual transmission of 20 per cent). This setting of the negative 
exposure means that 90 per cent modulation of light-valve spacing 
will not reduce the exposure beyond the lower limit, nor increase the 



[J. S. M. P. E. 

exposure as far as the upper limit of the straight line. The impor- 
tance of being able to use a high modulation of negative exposure will 
be evident when we come to discuss noise reduction. 

Fig. 1 1 exhibits an over-all construction on the same basis as that 
in Fig. 8, except that the lower right-hand quadrant is occupied by 
the curve of Fig. 1 . Printer lines are drawn such that for one of them 
a negative unmodulated exposure equal to 10 times the toe exposure 














K x 


















N N 



1 l-Bls 


A, IB 

s - . 





4 08 1 

? 1 

fi ? 


? -0 

8 -0 

4 ( 

1 1 
I 1 


8 1 










" // 








1 1 



1 | 





' 1 

! ' 

1 1 

| 1 




! ! 






















FIG. 11. Straight-line recording; over-all gamma = 1.4. 

shall appear as a positive projected density of 0.75; for the other, an 
unmodulated negative exposure 6.3 times the toe exposure appears 
also as a positive projected density of 0.75. 

The processing represented by Fig. 1 1 is commercially practicable 
and produces successful sound records. The over-all print curves in 
the upper right-hand quadrant are also adapted to pictorial require- 
ments; in this case the sound is not in conflict with the picture. 

The final print curves of Fig. 11, translated into projected print 


transmission vs. negative exposure, are drawn in Fig. 12. For con- 
venience the negative exposure is given in terms of the toe exposure. 
Just as in Fig. 9 in toe recording, we find here an S-shaped curve 
including a fairly straight portion. Curve A has this straight portion 
centered at a negative exposure equal to about 10 times the toe 
exposure, appearing as a positive projected transmission of 17 
per cent. The central exposure of the straight-line part of curve B 
is about 6 times the toe exposure and again corresponds to a pro- 
jected transmission of 17 per cent. We see here a point of resem- 
blance between toe recording and this approximation to straight- line- 
recording. In toe recording the negative exposure can vary from 
0.30 to 0.45 meter-candle-seconds atid produce a successful sound 
record, if the unmodulated negative exposure is in each case printed 
to a positive projected transmission of 42 per cent. In the straight- 
line record the negative unmodulated exposures may vary between 
6 and 10 times the toe exposure, provided the projected transmission 
of the unmodulated positive track is made 17 per cent. Whereas 
in the toe record negative modulation must be restricted, say, to 
45 per cent, in the recording represented by Fig. 12, 70 per cent 
negative modulation can be used without overstepping the straight- 
line limits of the final curve. 

The two curves of Fig. 12 show approximately the same volume for 
70 per cent modulation of the average negative exposure. This 
volume is proportional to 0.27 (average of A and B) whereas the vol- 
ume of the toe record is proportional to 0.44 (Fig. 9), a difference in 
output of 4.2 db. in favor of the toe record.* Offsetting this is 
the difference between the projected noise levels to be expected from 
the unmodulated positive tracks of the two types of record. Within the 
limits of 10 and 40 per cent projected unmodulated transmission 
the noise amplitude, combining the noise contributions of negative 
and positive, is proportional to the projected positive transmission. 
There is indicated for the toe record a noise level 7.8 db. higher than 
that of the straight-line record. This difference corresponds to the 
42 per cent transmission of Fig. 9 compared with the 17 per cent 
transmission of Fig. 12. 

For both types of record the tolerance of negative unmodulated 
exposure may be interpreted as a tolerance in emulsion speed or in 
bromide concentration of the developer, or in intensity of light source. 

* 4.6 db. if we are generous to the circles of Fig 9. 



[J. S. M. P. E. 

From the point of view of the negative record it is, strictly speaking, 
a tolerance in the location of a point on the H & D curve. 


The standard noise-reducing equipment closes the light-valve to 
a predetermined spacing when there is no input signal. When a signal 
current arrives at the light-valve terminals, provision is made to in- 
crease the spacing sufficiently to accommodate the incoming signal 
with adequate margin. It is not the purpose of this paper to discuss 
the adjustment of noise-reduction equipment, but to inquire what 
noise reduction may be expected of toe and of straight-line records 
without impairment of quality. The requirement should be adhered 
to that the negative exposure shall not fall below the limit of the 
straight line of projected print transmission vs. negative exposure. 


(A FIG 1 1) 

(B FIG 1 1) 

" ;^--7l->b-^F+7H.-. 



FIG. 12. Straight-line recording; sound reproduction characteristic. 

As a basis for comparison let it be assumed that the valve closure 
shall in each case be such that an incoming signal 20 db. below the 
level, which fully modulates the valve at its standard spacing, shall 
not drive the negative exposure below the straight-line limits of Fig. 
9 and Fig. 12, even if the noise-reduction equipment should fail to 
reopen the valve as rapidly as this incoming signal demands. At the 
normal valve spacing of 1 mil a sine-wave signal causing 100 per cent 
modulation changes the valve spacing by 1 mil above and below its 
unmodulated value. A sine-wave signal 20 db. lower than this full 
modulation opens and closes the valve by 0.1 mil, and it is this rapid 
movement in closing which must not reduce the negative exposure 
below the prescribed limit. 


In the toe record, where 45 per cent modulation of negative expo- 
sure is permissible, the noise-reduction device may close the valve 
spacing to 0.65 mil, in which case a further decrease in spacing of 0.1 
mil will not go outside the straight-line limit. Examination of the 
curves of Fig. 9 shows that this closure of the unmodulated valve 
spacing to 0.65 mil brings about a reduction in positive projected 
transmission equivalent to lowering the projected noise level by 6 db. 

Treating the curves of Fig. 12 in the same way we find that closing 
the normal 1 mil valve to 0.4 mil is permissible, since a further closure 
of 0.1 mil just reaches the lower limit of the straight line. This is 
an 8 db. reduction in valve spacing and results in a 10 db. reduction 
of projected print transmission. It is therefore concluded that a 
noise reduction of 10 db. is possible in the composite* processing 
represented by Fig. 11 and Fig. 12. 

The above conclusion regarding straight-line recording of this type 
has been often verified. Experimental toe records with the light- 
valve were made with adjustments of the noise-reduction equipment 
resulting in 9, 10, and 11 db. reduction of projected noise, showing in 
each case a distinct deterioration in quality and distortion of volume 
relations. These experiments roughly substantiate the statement 
that a 6 db. reduction in noise is all that can be expected of the toe 
record without incurring quality loss. 

Compared with the straight-line the toe record has the advantage 
of greater signal volume, but this is offset by its narrower range be- 
tween signal and noise level without noise reduction, and the smaller 
amount of noise reduction applicable without distortion. 

In actual projection, the experimental toe record without noise 
reduction was found to be more than 1 fader step and less than 2 
steps louder than composite straight-line records of the type here 
described. For the same level of dialog projection the ground noise 
of the toe record was somewhat more than 1 fader step louder than 
the ground noise of the straight-line record. Volume indicator mea- 
surements of dialog level and ground noise level showed for the toe 
record a range of 24 db. be ween dialog and noise. If we can take 
8 db. as the logarithmic difference between voice peaks and general 
voice level as read on the volume indicator, we have a range of 
32 db. between the limiting swing of positive transmission and 

* By "composite" is meant the processing of the sound positive to an over-all 
gamma greater than unity, in part offsetting this by appropriate use of the 
positive toe, the negative exposure being confined to the straight line. 


the ground noise amplitude. This is an amplitude ratio of 40 to 1. 
If the double amplitude of modulation of projected positive trans- 
mission is 0.44, then the double amplitude corresponding to the 
ground noise is 0.01 1 . This is a variation of less than 3 per cent of the 
average projected transmission shown in Fig. 9. If the noise were 
due exclusively to the film itself the variations in transmission cor- 
responding to the ground noise would be almost imperceptible to 
the eye. 


In the composite straight-line record of Fig. 11 and Fig. 12 the 
indicated limits of negative exposure in both curves A and B are 
within the limits of the straight-line part of the H & D curve. The 
over-all gamma is 1.4 and by itself would result in a curve of projected 
print transmission increasing more than proportionally to the nega- 
tive exposure. This curve, convex to the axis of negative exposure, 
is partially rectified by printing on a portion of the positive toe. No 
use is made of the negative toe ; this would exaggerate the convexity 
of the curve at the lowest negative exposures. 

An over-all projected gamma of unity would result from a negative 
light- valve gamma of 0.36 in place of the negative curve of Fig. 11. 
The classical specifications require that only the straight-line part of 
this curve be used for the negative exposure and that it be printed 
to lie wholly within the straight-line part of the projected print curve. 

Since for a Cinex gamma of 2.1 the printer curve is seldom straight 
beyond a visual density of 2.4, the maximum scale of negative densi- 
ties printable on the positive straight line is 0.74 (see printer curve of 
Fig. 8 or Fig. 11). For 90 per cent modulation of negative exposure, 
confined to the straight-line portion for gamma = 0.36, the negative 
density range is 0.36 X log 19 = 0.46. There is, therefore, a latitude 
of 8 printer points in printing this negative: 0.74 0.46 = 0.28, and 
3 printer points correspond to 0.10 in negative visual density for a 
printing coefficient of 1.2. 

Fig. 13 shows the projected printer curve rotated 90 degrees to the 
left and negative lines of slope 0.36. These lines are of such length 
as to cover a range of 1.28 in log negative exposure, corresponding to 
90 per cent modulation of a central exposure equal to 10 times the 
toe exposure. The actual H & D curve of gamma = 0.36 begins to 
be straight at a visual density of 0. 14 ; for convenience the lines drawn 
in Fig. 13 are located to represent the lowest and highest printer 

Aug., 1931] 



points at which they can be printed without going outside the straight 
part of the printer curve. 

At the right in Fig. 13 are the corresponding curves of positive 
transmission vs. negative exposure for the limiting printer points. 
Each of these curves is straight over 90 per cent modulation of the 
central negative exposure indicated. Comparison of the two curves 
shows the unmodulated positive projected print transmission to be 
0.07 for the lightest print and 0.012 for the darkest print consistent 
with the requirement that the negative shall be printed on the straight- 
line part of the printer curve. The volume difference between these 
two prints is therefore about 15 db. The maximum permissible noise 
reduction is determined by the requirement that a signal 20 db. be- 
low full modulation of the normal valve spacing shall not cause 
the negative exposure to fall below the toe exposure; 14 db. re- 







GT>036 PC -12 

























28 24 20 16 12 08 04 

04 08 12 1 

M*uoe : " a 





^eG CXP/TOC txp 

FIG. 13. Classical straight-line recording. 

duction in valve spacing closes the valve to 0.2 mil. This is the maxi- 
mum permissible and corresponds to 14 db. reduction in ground noise. 
The signal volume to be expected from the lighter of these prints 
is more than 6 db. lower than the volume obtained from the composite 
record of over-all gamma = 1 .4 and negative modulation 70 per cent. 
At the same time the noise level is more than 7 db. lower (unmodu- 
lated projected transmission of 0.07 compared with 0.17). The vol- 
ume range between signal and noise is therefore about 1 db. greater 
in this record than in the composite. 


The types of light-valve records discussed may be called toe, com- 
posite, and classical. Each with its appropriate negative exposure, 
negative modulation, and printer point is capable of giving excellent 



[J. S. M. P. E. 

sound reproduction. Only with the third type, the classical record, 
is it possible to control signal volume over a considerable range with- 
out distortion by choice of printer point. This will be clear from an 
examination of Fig. 9 and Fig. 12. It will be evident that for both 
toe and composite types, varying the printer point on a given average 
negative exposure will involve distortion unless the negative modula- 
tion has been narrowly restricted. For practical reasons only the 
lightest possible print of the classical record would be produced for 
theater use. 

The numerical estimates of signal volume given for the three types 
of record show the toe record to be approximately 1.5 fader steps louder 







_ *20.8 











= 6 

t -10 







N.R. - 10 



N.R. r|4 

* -22.2 






FIG. 14. Projection levels. Light-valve records. 

than the composite and the latter 2 fader steps louder than the lightest 
print of the classical record. Signal-to-noise ratios are estimated as 
24 db. for the toe,* 28 db. for the composite, and 29 db. for the classi- 
cal. The permissible reduction in projected noise level is estimated 
to be 6 db. for the toe, 10 db. for the composite, and 14 db. for the 

In a theater of 500,000 cu. ft., seating about 2000 persons, the 
level of loud dialog projection is about +20 db. electrical power 
delivered to the Western Electric loud speakers. In such a theater 

* Actual measured range of experimental toe record between dialog and noise. 


the audience noise is at a level of 15 db., while the noise due to 
theater equipment in the empty house is about 25 db.* 

Fig. 14 exhibits the comparative levels of dialog projection" and of 
film noise with and without maximum permissible noise reduction 
for the three types of record when the fader is set to give approximately 
the same projection level for dialog. In a theater of the size assumed, 
the composite type of record would usually be projected at step 10 
on the fader. The amplifiers would then deliver about +20 db. to the 
loud speakers. If fader step 10 is acceptable for the composite rec- 
ord, the fader could be set at 8 for the toe record and would have to 
be raised to 12 for the classical print restricted to the straight line of 
the printer curve. 

Fig. 14 indicates that 6 db. noise reduction, the maximum permis- 
sible on the toe record, would leave the ground noise louder than the 
audience noise when the dialog level is +20. Ten db. noise reduction 
in composite records reduces the ground noise to a level below the 
audience noise, whereas the classical type of record with 14 db. per- 
missible noise reduction reduces the noise level almost to that of 
theater equipment. 

Of these three records only the composite type represents sound 
processing nearly like that of the picture and thus is the only type 
of processing which is possible for newsreel records, where sound 
and picture negative are made on the same film. In this case the usual 
picture development of both negative and positive can be used, re- 
quiring for its success a proper choice of sound track negative ex- 
posure, of negative modulation, and of printer light, possibly also a 
suitable filter when printing the sound negative. The considerations 
which have been set forth in this paper will enable any one to deter- 
mine the proper treatment of the sound record. 


(1) The commercial types of variable density sound records on 
film have been analyzed and compared with the classical specifications 
for distortionless sound reproduction. 

(2) Sensitometric data have been discussed and it is shown that 
the product of positive and negative sensitometer gammas derived 

* These levels are referred to 0.006 watt as zero level. Audience noise and 
theater noise are stated in terms of their equivalents in power input to the loud 


200 DONALD MACKENZIE [j. s. M. P. E 

from plots of visual diffuse density vs. log exposure is not equal to 
the over-all projected gamma of the sound track. 

(3) The method of constructing the over-all characteristic has been 

(4) The noise reduction applicable without distortion has beei 
considered for each type of sound record. 

(5) The projection levels of dialog and ground noise with the rela- 
tive fader settings have been estimated with reference to an average 

In any sound film processing we have to consider the positive and 
negative development, the negative unmodulated exposure and per- 
centage modulation, and the exposure of the unmodulated positive 
track. Fixing the positive and negative gammas leaves us free to 
choose the negative exposure and the printer point. In the toe record 
there is found to be a considerable latitude in the location of the 
negative unmodulated exposure on the negative H & D curve. For 
all negative exposures within this latitude there is one optimum den- 
sity for the positive print. Similarly in straight-line records of over- 
all gamma = 1.4, there is a wide latitude in choice of negative ex- 
posure, again with a definite positive density for a successful print. 
In each of the above cases there is a definite limitation on the per- 
centage modulation of negative exposure: 45 per cent for the toe 
record where positive and negative gammas are each 2.0 by daylight 
time scale, 70 per cent for the composite straight-line record of nega- 
tive gamma 0.50, positive gamma 2.1 by Cinex time scale. It is ob- 
vious that for composite straight-line records developed to other 
values of negative and positive gamma, there exist similar optimum 
combinations of negative exposure, negative modulation, and print 
density. It will be found that the combination suitable for the case 
considered in the text is also suitable for positive and negative 
gammas, each 5 per cent higher or lower than the particular values 

Increase in signal volume obtainable from the straight-line records, 
either composite or classical, is obtainable only by lowering the con- 
trast to which the positive print is developed. Since this positive 
contrast is determined by the requirements of picture processing, 
louder variable density sound records must wait for a softer print 
development unless sound quality is sacrificed. 

In Hollywood, in January, 1931, laboratory "X" used a sound nega- 
tive developer giving a printing coefficient of 1.08. In this develop- 


ment the light- valve gamma of 0.47 was easily obtainable on East- 
man positive film. At the same time laboratory "Y" used a positive- 
bath and a combination of filter and lamp in the printer, which gave 
a true printer gamma of 1.58. The negative of laboratory "X" 
printed at laboratory "Y" would result in an over-all projected gamma 
of unity. The unmodulated negative exposure could have been made 
10 times the toe exposure, permitting 90 per cent modulation about 
this average. The printer point at laboratory "Y" could have been 
chosen for an unmodulated positive transmission of 0.25 visual 
diffuse. This would have meant a projected print transmission of 
0.17, giving the same noise level as in the composite record described 
above, and a signal volume proportional to 0.30. The 90 per cent 
negative modulation would have been reproduced without dis- 
tortion, the signal would have been 1 db. louder than in the com- 
posite record just mentioned, and 14 db. noise reduction could have 
been used without distortion. 

The toe-record volume is not seriously affected by a slight variation 
in gamma, and is about 2 fader steps higher than the composite 
straight-line record, over-all gamma = 1.4. At the same time the 
signal-to-noise ratio on the toe record is decidedly less than on the 
composite straight-line record, and is limited by the maximum 
noise reduction applicable without distortion. Wherever signal 
volume is the first consideration, the toe record is preferable. In 
the usual case, however, the most important consideration is the 
signal-to-noise ratio. In this respect the advantage is decidedly 
with the straight-line recording. 

Of the two straight-line types examined, the composite record more 
closely resembles the picture technic. The classical recording, 
over-all gamma = 1.0, is exceptionally suited to the processing ol 
sound records which can be treated independently of the picture. In 
this case the same development can be used for the sound negative 
and the sound positive, resulting in an over-all projected gamma of 
unity with maximum signal volume of the sound print. When the 
sound negative is made on positive emulsion, toe recording is called 
for by light sources of restricted intensity, and has the advantage of 
saving the separate sound negative bath. Where a light source of 
sufficient intensity for straight-line recording is available, the ad- 
vantages of the toe record are offset by the greater volume range be- 
tween signal and noise which is obtainable on the straight line. 

All things considered, the advantage lies with the straight-line rec- 


ord. Although lower in volume than the toe record, it has inherently 
a greater volume range for the same standard of quality, and this ad- 
vantage is still further increased by applying noise-reduction methods. 
In the discussion just concluded nothing has been said regarding 
the frequency characteristic for the reason that the high frequency 
cut-off for any record is determined by a number of circumstances 
independent of the processing technic; nor has anything been said 
regarding the practical problems of photographic chemistry and de- 
veloper maintenance which must be dealt with in order to insure the 
most successful use of the photographic emulsion and, in the particular 
case of the toe record, the greatest stability in the shape of the H & D 
curve. It has been assumed that a uniform development was avail- 
able for each type of processing, which means that adequate precau- 
tions were assumed to avoid variation in bromide concentration and 
in activity of the developing agent. It is commercially possible to 
maintain the developer composition by appropriate boosting, but the 
improvement in development formulas for both picture and sound 
record processes is a chemical problem of major importance with 
which the present paper does not deal. 


1 JONES, L. A. : "On the Theory of Tone Reproduction with a Graphic Method 
for the Solution of Problems," /. Opt. Soc. of Amer., 4 (1920), p. 420. 

2 RENWICK, F. F.: "The Underexposure Period in Theory and Practice," 
Phot. Jour., 53 (April, 1913), p. 127. 

3 JONES, L. A., AND WILSEY, R. B.: "The Spectral Selectivity of Photographic 
Deposits," /. Franklin Institute, 185 (Feb., 1918), p. 231. 

4 TUTTLE, C., AND McFARLANE, J. W.: "The Measurement of Density in 
Variable Density Sound Film," /. Soc. Mot. PicL Eng., XV (Sept., 1930), p. 345. 


Summary. A system for reducing ground noise on variable area records 
was described by Townsend, McDowell, and Clark in February, 1931. The pre- 
ferred method employs a shutter mounted on the recorder which intercepts part of the 
light and reduces the sound track to a width just sufficient at all times to accommodate 
the modulation. A commercial design of shutter has been developed for this system* 

A motor for actuating the shutter has been designed in which an iron armature 
moves in a direction parallel to the pole faces so as to change the areas rather than 
the lengths of the air gaps. Such a motor combines the special advantages of the 
moving coil type, namely, long throw and stability, permitting the use of a highly 
flexible spring, and the advantages of the iron armature type, namely, light field 
structure and large winding space. Electromagnetic damping is provided. The 
resulting motor gives full deflection on about 20 milliamperes and lias the desired 
speed of action. It can be attached to the optical system of the RCA Photophone 
type PR-4 Recorder with no operations on the latter except drilling and tapping 
two screw holes. 

A system for reducing ground noise on film records was described 
by R. H. Townsend, H. McDowell, and L. E. Clark, in papers read 
before the Academy of Motion Picture Arts and Sciences, and pub- 
lished February, 1931. The system consists essentially of reduc- 
ing the area of clear film in the sound track. In a sound reproduc- 
ing system employing photographic records, ground noise is caused 
principally from photoelectric cell hiss (shot effect), variations of 
light due to graininess in the film, and dirt and scratches on the 
film. The photoelectric cell hiss is roughly proportional to the 
amount of light entering the cell. Irregularities in translucency 
due to imperfect distribution of film grains are negligible with un- 
exposed film, increase to a maximum when the density is such as 
to cut off half the light, and become less again as the transmitted 
light approaches zero. Noise due to graininess in the film is usually 
slight unless the normally clear part of the film is fogged or the nor- 

* Presented in the Symposium on Sound Recording at the Spring, 1931, 
Meeting at Hollywood, Calif. 

** RCA Victor Co., Camden, N. J. 


204 E. W. KELLOGG AND C. N. BATSEL [J. S. M. P. E. 

mally black part is thin enough to permit considerable light to pass. 
With proper recording and printing the dark areas are sufficiently 
dense to be a negligible factor in producing noise. The major part 
of such noise as is traceable to graininess is due to fog in what should 
be the clear area, and is reduced by diminishing the width of the 
clear area. The noise due to dirt and scratches is also roughly 
proportional to the amount of light passing through the film. With 
normal recording, half the width of the sound track, on the average, 
is black and half is clear. Noise might result either from trans- 
parent spots in the black area or from dark spots in the clear area. 
The former, however, are relatively rare. If the negative from 
which the print is made is in good condition, there are practically 
no clear spots in the blackened area of the print. Scratches and 
specks of dirt over the dark part of the track tend to make it blacker, 
and have little effect. On the other hand, a projection print rapidly 
accumulates dirt and scratches and these show up as dark spots on 
the clear area. If the clear area is reduced in width, a correspond- 
ing fraction of the sound produced by these spots is eliminated. 
On the average, the energy represented by the ground noise is reduced 
in proportion to the reduced width of clear track. 

While with 100 per cent modulation the full width of track is 
utilized, there are long stretches of comparatively small modulation 
during which the clear area in a standard recording is unnecessarily 
wide. L. T. Robinson, of the General Electric Co., proposed a 
method of reducing the width of the clear portion to an amount 
just sufficient to accommodate the modulation, by rectifying a portion 
of the audio-frequency current and passing the rectified current 
through the galvanometer in such a direction that the recording 
light spot would vibrate about a new mean position which is dis- 
placed from the center of the sound track. The result of this zero 
shift system is a sound print which appears as in Fig. 1. Experi- 
ments indicated that this accomplished the desired result, providing 
a substantial reduction in ground noise. C. R. Hanna, of the West- 
inghouse E. & M. Co., independently proposed and worked out 
substantially the same plan. 

The system just described is open to the criticism that when the 
modulation is small the recording is displaced from the center of 
the track. In the case of imperfectly adjusted projectors it some- 
times happens that the scanning beam does not cover the full width 
of the sound track and this might result in distortion or cutting off 

Aug., 1931] 



of the small amplitude recordings. It would be safer to keep the 
recording in the middle of the track and cause a darkening of the 
unused portion of the track by bringing in the margin as shown in 
Fig. 2. H. McDowell, Jr., noted the drawbacks of the zero shift 
system and proposed the use of an auxiliary device in the form of a 



FIG. 1. Sound track made with variable bias of galvanometer. 

shutter which would intercept part of the light used in recording, 
and give a sound print of the type shown in Fig. 2. A number of 
successful recordings have been made using McDowell's shutter. 
The advantages of this system were generally recognized and com- 
mercial designs of shutter equipment were undertaken. 



FIG. 2. Sound track made with shutter. 

The original shutter employed a moving coil in a magnetic field. 
While this constituted an excellent driving motor it appeared to the 
writers that the moving coil was not necessarily the best choice of 
driving system. It has two drawbacks. The air gaps are necessarily 
long, and if a strong field is to be provided it requires either an elec- 
tromagnet or a very large permanent magnet. In the second place 
the space available for the coil is generally small and it is difficult 
to put on enough turns of wire to make the device work directly 

206 E. W. KELLOGG AND C. N. BATSEL [j. s. M. p. E. 

from the plate current of a moderately small radiotron. The features 
of the moving coil drive which have given it preeminence in the 
loud speaker field are: (1) freedom from instability, permitting an 
extremely flexible mounting which enables the loud speaker to 
furnish good response at very low frequency, and (2) low induc- 
tance, favoring the response at high frequency. Neither of these 
factors applies in anything like the same degree in the case of the 
shutter. A moderately stiff mounting spring would be employed 
since the shutter must be spring controlled rather than inertia con- 
trolled in order that the same current may produce the same deflec- 
tion whether that deflection is reached quickly or slowly. Very 
low inductance is not essential, for the shutter need not respond at 
high frequency. Its movements must be too slow to produce per- 
ceptible sound in the reproducing system. Assurance against too 
rapid movements of the shutter is afforded mainly by filters in the 
electrical circuit between the rectifying system and the shutter. 
Inductance in the shutter winding may be considered simply as 
part of the electrical filter system. In view of these considerations 
it appears that if a reduction in field magnet requirements can be 
obtained at the price of somewhat stiffer springs and of increased 
inductance in the armature winding, such a change is desirable. 
If, in addition to a lighter field magnet, greater winding space can 
be obtained, this would be a further advantage. 

The balanced armature type of motor, widely employed until 
recently for loud speakers, offers the advantages of short air gaps 
(and therefore light field magnets) and of less limited winding space, 
these features having been obtained at the cost of high winding in- 
ductance. Stability problems, however, impose serious limitations 
on the design of all magnetic motors in which an iron armature moves 
toward and away from the poles of a magnet. The armature mount- 
ing must be very stiff in order to hold the armature in the central 
position, and in view of the short gaps, only very small movements 
can be tolerated. The stiff mounting limits the sensitivity and the 
small permissible throw requires that the shutter vane be mounted 
on the end of a very long arm to obtain the required movement. 
This movement is of the order of Vs inch in the case of the shutter 
for mounting on the optical system of RCA Photophone recorders. 
Such a long arm means that considerable mass must be moved, 
which tends to make the action of the shutter sluggish in spite of 
the stiff spring. 


Consideration of the principles of design of electric generators 
and motors leads to the conclusion that a third type of motor offers 
the advantages of the moving armature construction without its 
drawbacks, namely, one in which an iron armature is employed, but 
in which the air gaps change in area instead of length. 

It is of interest to note that in the design of electric motors the 
formula for the force per unit length of conductor applies without 
modification whether the conductor is on the surface of a smooth 
armature or in the bottom of a deep slot. The conductor in the 
bottom of the slot is not itself in a strong magnetic field and yet 

motor designers employ the familiar formula F = for the force 

developed. By winding the armature conductors in slots it has 
been possible to increase the winding space and at the same time 
shorten the air gap, thus reducing the excitation requirements. By 
way of illustration compare the field structure of one of the old 
Edison bipolar dynamos with that of a modern motor. These 
advantages in the design of motors have been secured at the price 
of increased armature inductance. 

As a further illustration of the principle involved, consider the 
case of a single conductor in a magnetic field. The formula for the 
force exerted on the conductor does not consider the length of the 
air gap in which the conductor is placed, although the longer the gap 
the smaller is the change of field intensity produced by the current 
in the conductor. If a conductor carrying 10 amperes is in a gap of 
0.5 cm. length having a field intensity of 10,000 gausses, it will in- 
crease the flux density on one side by 4?r gausses or to 10012.6 gausses 
and reduce it on the other side to 9987.4 gausses. The same current 
in a conductor in an air gap 0.25 cm. wide, having the same initial 
field intensity, would increase the flux density on one side by 
gausses or to 10025.2 gausses, and decrease it on the other side to 
9974.8 gausses. Yet, the force on the conductor is the same, namely, 
10,000 dynes per centimeter of conductor length. Any paradox in 
this situation disappears if we calculate the force on the conductor 
in terms of the side-wise push of a magnetic field. This push in dynes 

B z 
per square cm. is given by the formula which is exactly the same 

formula as that for length-wise pull. The force on the conductor 
is the difference between the pressures of the fields on the two sides 
of the conductor, calculated over an area equal to the air gap length 



[]. S. M. p. E. 

multiplied by the length of conductor in the field. Thus for the 
0.5 cm. gap the force is 0.5 t 10012 ' 6 ) 2 " (" 87 " 4 ) 2 = i ,000 dynes 


, (10025.2) 2 - (9974.S) 2 
and for the 0.2o cm. gap the force is 0.2.) 


10,000 dynes, for / equal to unity. If the air gap length is reduced, 
the reduction in area of pushing field just compensates for the in- 
creased field differential produced by the current in the conductor. 
With the short air gap the main field can be produced with fewer 
ampere turns, and therefore a lighter field structure, but since the arma- 
ture conductor causes more change in flux linkage, it shows a higher in- 
ductance. If the force on a motor conductor is calculated in terms 

[ \TO/?S/ONAL 

r~k^ ^ 



FIG. 3. Relation of shutter to optical system. 

of the side-wise push of a magnetic field, it is found (neglecting re- 
luctance of the iron) to be independent of whether the conductor 
is located on the surface of a smooth armature or in a slot. By 
putting the conductor in a slot a very short gap may be obtained 
without sacrificing winding space. 

It appears that the advantages of a lighter field structure in a 
motor for the shutter can be obtained in a design which closely re- 
sembles the moving conductor type of motor but which employs a 
short gap obtained by placing the conductors in slots. It is obvious 
that so far as the principle goes, it makes no difference which part 
moves and which is held stationary. In the present shutter motor, 
the active conductors and teeth are stationary while the part most 
nearly corresponding to field pole face is movable. 

Aug., 1931] 




The construction of the shutter motor is shown in schematic form 
in Fig. 3. The resemblance to an electric motor appears greater if 
we think of the moving part as a single piece of iron. (Substituting 
aluminum for the central part is one of the liberties which can be 
taken in view of the limited movement.) Considering either air 
gap alone, the moving element corresponds to a field pole and the 
stationary pole pieces to a pair of armature teeth. 

Two pairs of pole pieces are employed, each pair resembling an 
ordinary telephone receiver except that the permanent magnet im- 
parts the same polarity to both poles of the pair. In the i 

FIG. 4. General arrangement of magnetic shutter. 

tion the two upper poles are both TV and the two lower poles are 
both 5 in polarity. The moving element consists of a pair of small 
iron bars riveted to a duralumin tongue which is pivoted by means 
of a torsion strip in such a way that it can move readily in a direction 
parallel to the pole faces but can very strongly resist any movement 
which would tend to change the lengths of the air gaps. The duralu- 
min tongue carries an extension in the form of an aluminum tube on 
the end of which is a flat vane. In the normal position each of the 
iron bars is about half way within the space between opposing pole 
tips. The magnetism exerts a force on the bar tending to bring it 
wholly within the space between the stationary poles. Thus the 



[J. S. M. P. E. 

bar on the left is pulled toward the left while the bar on the right is 
pulled toward the right. The condition of balance is not of the 
unstable kind which is encountered in magnetic devices in which the 

FIG. 5. Details of the shutter mechanism. 

FIG. 6. View of shutter with cover in place. 


air gaps change length instead of area. A very stiff spring is not 
required to hold the bars at the mid-position with respect to right 
or left movements. This being the case, strong forces are not re- 
quired to produce moderate deflections and, therefore, good sensi- 
tivity is obtained. The coils are connected so that with current 
flowing in one direction through the four coils the poles at the left 
are strengthened and those at the right are weakened, thus pulling 
the movable element to the left, while a reverse current strengthens 
the poles on the right and weakens those on the left, causing the 
armature to move to the right. Fig. 4 shows in schematic form 
the manner in which the shutter fits into the optical system. Fig. 5 
and Fig. 6 show the general construction and appearance of the 

It is desirable in case of a rapid rise in modulation which causes 
a fairly quick movement of the shutter, that any oscillation which 
the latter tends to execute shall be quickly damped out. It was 
found possible to provide the desired damping electromagnetically 
by making the spool heads of copper. 

The pole pieces are mounted in a bracket to which the torsion 
spring is attached. The total air gap spacing is fixed by the machin- 
ing of the bracket. The adjustment of the armature in the middle 
of the space is accomplished when the torsion spring is clamped. 
The cover provides practically complete protection for the delicate 
vane. A mechanical zero setting is not necessary. The shutter 
is operated directly by the plate current of a pair of UX-171A radio- 
trons, about 20 milliamperes giving a deflection of l /& inch at the edge 
of the shutter vane. The amplifier circuit is so arranged that the 
current decreases as the modulation increases. The adjustment of 
the shutter, therefore, consists in regulating the current through the 
shutter to bring the shadow close to the middle of the sound track 
when there is no modulation. The gain of the amplifier is then 
adjusted so that the shutter is completely out of the way when 
there is full modulation. 

The shutter is designed to be mounted on the optical system of 
RCA Photophone recorders Type PR4-B, with no operations on the 
optical system except drilling and tapping two holes for attachment 


A paper entitled "Noise Reduction with Variable Area Recording," by B. Kreuser, 
describing the theory and application of the system of noiseless recording to which the 

212 E. W. KELLOGG AND C. N. BATSEL [J. s. M. p. E. 

shutter described in this paper is applied, was published in the June issue of the 
Journal. These two papers were presented consecutively at the Spring Meeting at 
Hollywood, and the following discussion applies jointly to the two papers. 

MR. FELSTEAD: Has the noise reduction system any effect on the laboratory 
technic of development? 

SPEAKER: With variable area recording the laboratory processing is handled 
in the same manner as it was without the ground noise device. 

MR. MACKENZIE: What is the volume range obtained between the full signal 
and the unbiased unmodulated track? 

SPEAKER: Probably 40 to 45 db. 

MR. MACKENZIE: Has it been measured? 

SPEAKER: Not to the best of my knowledge, to any degree of accuracy. 
Many features are involved in a problem of that kind, such as house noise, etc., 
and it is quite possible, employing a noiseless recording system, to operate at 
levels lower than that of the house noise. Such low levels are, of course, useless. 

MR. SILENT: I would like to call attention to certain differences in noiseless 
recording effects when using variable area and variable density tracks. The 
variable area method of recording requires an application of electrical units to 
the electrical circuit and the addition of a mechanical unit to the recorder itself. 
The variable density method of noiseless recording requires the similar applica- 
tion of an electrical unit to the transmission circuit, but no additional attach- 
ment to the recorder itself, since the light valve used in recording performs a 
function in cutting off the light similar to that of the mechanical attachment 
in the variable area method. In the variable area method the light normally 
covers but one-half the sound track in order to provide means for modulation, 
and in addition a shutter cuts off the light which is not necessary to carry the 
required modulation. We can then plot, in the form of a curve, the noise which 
results from this track against the amount of light which passes through it (see 
Fig. 1 of discussion). The amount of light which passes through it we may re- 
gard, of course, as proportional to the width of the clear area. The narrower 
the track, the less the noise which results from the movement of the film itself in 
front of the photoelectric cell. The noise due to the cell is small compared 
with that due to the film. Now, if we cut the width of the track in half we find 
that the noise output is reduced by 3 db., and if we cut the width of the track 
in half again, we find that the noise is reduced 6 db. Obviously, we can change 
the amount of light which passes through the track, not by reducing the width 
of the track, but by increasing its density, as is done in the variable density 
system of recording. Suppose we plot the noise received from the variable 
density track against the amount of light passing through it, and, instead of de- 
creasing the width, increase the density, we immediately obtain a curve having 
twice the slope. When we have reduced the amount of light to 50 per cent of 
the original value, we have a 6 db. decrease in the noise due to the track; when 
reduced to 25 per cent we have 12 db. reduction in noise. In the upper portion 
of the curve there is a slight discrepancy, since it is not linear above the 50 per 
cent point. That, however, is of no consequence in this consideration. Now, 
suppose we want to obtain on the variable area track a 10 db. reduction of noise. 
This requires that we reduce the width of the clear space to Vio its normal width. 

Aug., 1931] 



But suppose that in the variable density process we also wish to obtain a 10 db. 
reduction of noise. In this case we need only decrease the spacing of the light- 
valve by a voltage ratio corresponding to 10 db., which is 0.316. In other 
words, in the variable area method of recording we reduce the width of the clear 
space on the sound track to 0.1 its normal value for a 10 db. noise reduction, 
whereas in the variable density method we need decrease the spacing of the light- 
valve to only 0.316 its original value for a certain definite amount of noise 
reduction. We have 3 times as much space for the clashing of the valves in the 

100 80 60 40 20 10 6 6 4 



FIG. 1. Graph illustrating Mr. Silent's discussion on noise relations 
of variable width and variable density methods. 

variable density method of recording as we have for overshooting of the vibrator 
in the variable area method of recording, which represents a 10 db. increase of 
margin against overloading of the recording unit itself. 

MR. TOWNSEND: I would like to call attention to one point which I believe 
was clouded by the last discussion. In considering the variable area track, half 
the track is normally black. In other words, it is necessary to decrease the area 
of only one-half the track, because normally half the track is already black, 
and actual measurements would differ considerably from those given. In the 
variable density track it is necessary to reduce the light transmitted by the entire 
width of the track and not half of it. 

214 E. W. KELLOGG AND C. N. BATSEL [J. s. M. p. E. 

MR. SILENT: The half width of the variable area track corresponds quite 
exactly to the carrier density of the variable density track. 

MR. HUTCHINS: The figures given by Mr. Silent are not true for Vio the 
width of the clear portion. The theoretical noise reduction, when the clear 
portion is reduced to Vio its normal value, is 20 decibels, and the actual prac- 
tical decrease is somewhat less than this value due to imperfect transparency and 
opacity of the track. I believe the actual noise present and the electrical power 
corresponding to that noise is directly proportional to the width of the sound track 
if the scanning beam across the area of the track is uniform. Variations from 
that are usually due to non-uniformity in the width of the scanning beam. Thus, 
non-uniformity in the scanning beam introduces distortion in the wave shape of 
the variable area track, but not in the variable density track. 

MR. MACKENZIE: Perhaps Mr. Townsend has some measurements which will 
indicate the volume range obtained between a fully modulated dialog recording 
and a noise reading taken without modulation. 

MR. TOWNSEND: I do not have those figures available. The best commercial 
results, if you permit that term, show a range extending about 45 db. above 
ground noise in a very quiet room. In a room in which the ordinary noise level is 
10 db. or less, we find that the signal strength of a dialog modulated signal at a 
reasonable distance from a speaker, will increase to a limit of about 45 db., which 
is usable. 

MR. SHEA: We have made quite an extended series of measurements in connec- 
tion with the use of wide sound track for the so-called wide film. According to 
statistical theory, assuming the random addition of the noise currents it was 
expected that by doubling the track from, say, 100 to 200 mils, about a 3 db. 
increase of volume range would be obtained. While not very great, this is 
quite appreciable. We made measurements on tracks of various widths from 
5 mils to 300 mils using a device which explored portions of the track. The 
theory checked out very closely over ranges of transmission as high as 50 per cent. 
In the variable area method the transmission is much higher. It may happen 
that conditions are somewhat different, but Mr. Silent's figures do hold, in so far 
as unmodulated track is concerned, up to a transmission of 50 per cent. 

MR. SLAUGHTER: Speaking from the standpoint of one who uses the methods 
of reducing ground noise, I might say without hesitation that these methods 
have resulted in improvements in reproduction which are very gratifying. At the 
present time there are certain limitations in the matter of minimum noise con- 
ditions which prevail on the motion picture sets and the new methods of reducing 
ground noise are entirely capable of fully capitalizing on the noise reduction 
down to the limits set by studio noise conditions. 

MR. CECCARINI: Mr. Slaughter's point of view is correct. In actual practice 
it does not seem feasible to reduce the noise beyond a certain degree because of the 
minimum noise conditions which prevail in motion picture sets, to which might be 
added the noise conditions in auditoriums and theaters in which sound is 
being reproduced. 

With regard to recording sounds of low volume, it seems to me that in the case 
of the variable area method, the width of the track can be reduced to a very 
small value, thus realizing any degree of noise reduction without changing the 
wave shape of the sound being recorded. In fact, no relation exists between 


wave shape and reduction of noise in variable area recording for a properly ad- 
justed condition, excepting at the beginning of each sound a fact which is com- 
mon to both systems. With the variable density method using the double ribbon 
valve, there is a danger of short circuiting the ribbons unless precautions are taken. 
Furthermore, very low level sounds are recorded in the under-exposure region 
of the negative characteristic. This corresponds to distortion of wave shape, 
because the over-all contrast under these conditions would be far from unity. 
Moreover, the underexposure region of the negative corresponds to heavy density 
in the positive, and the spreading effect of heavy densities tends to obliterate 
these minute sounds, thus destroying linearity of volume. Two sounds, having a 
certain volume difference when heard in the monitor during recording, will ap- 
pear to have a greater volume difference in the finished record. On the basis of 
these considerations the difference in "rate" of noise reduction pointed out in 
previous discussions, loses its real significance, and the controversy becomes one 
of "limits." Having had the opportunity to make extensive measurements with 
both systems, I am convinced that the reduction of noise by the variable area 
method can be extended to a limit far beyond that which is feasible with the 
variable density method, without depreciation of quality. 

MR. HOPPER: With the advent of noiseless recording, all theaters which had 
been equipped with Western Electric equipment have been made the centers of 
extensive campaigns for reducing noise. The most common sources of noise in 
the theater are the ventilating systems, fans and other house equipment, and 
the projection equipment itself. Many theaters which are acoustically treated 
also have the projection booth treated to reduce noise. Recent developments 
in electro-acoustical devices in the Bell Telephone Laboratories have made 
it possible to determ ne the various noise levels very readily by experimental 
methods, and this has led to a study of means for reducing them. 

MR. LAMBERT: Noiseless recording is apparently more valuable in re-recording 
than in original recording. In original recording, we do not usually have ap- 
preciable surface noise, but when this noise is doubled, or approximately so, 
in some instances in re-recording, it may then become objectionable. Our ex- 
perience has shown that often noiseless recording methods will so reduce the 
surface noise of a re-recorded scene that it can be recut without using noiseless 


Summary. This paper describes a simple cine- photomicro graphic apparatus 
built for the Bio-Cinema Research Laboratory at the Massachusetts Institute of Tech- 
nology. The essential feature of the apparatus is an optical system which permits 
the separation of the microscope and illuminating system from the camera and its 
driving mechanism. The microscopist is thus enabled to use the microscope in the 
ordinary manner for visual work and has merely to insert the unit under the camera 
when the subject is ready to be photographed. In this way the same camera can be 
used interchangeably with a number of microscopes. 

The combination of a motion picture camera and a microscope 
results in an exceedingly useful tool for both instruction and research. 
A preliminary investigation of its possibilities was made here during 
1919 and 1920 by one of the present authors in collaboration with 
Professor C. E. Turner of the Department of Biology. Films were 
made of protozoa feeding on bacteria, the hatching of ambystoma 
eggs, and many similar subjects which are either difficult to show to 
a large audience or which change so slowly that the action, to be ap- 
preciated, must be accelerated by the camera. The encouraging re- 
sults of these early experiments led to the establishment of our Bio- 
Cinema Research Laboratory. 

The purpose of the present paper is to describe a simple form of 
cine-photomicrographic apparatus, which was designed and 'built 
for this laboratory, and has been in use for approximately two years. 

Since every biologist is necessarily proficient in the visual use of 
the microscope, an attempt was made in designing this apparatus to 
utilize as much of his present technic as possible. This was accomp- 
lished by employing an optical system which enables him to study 
the subject under the microscope in the ordinary manner and then, 
when satisfied with the appearance of the field, to swing the micro- 
scope quickly into position under the camera and make the ex- 

*Presented at the Spring, 1931, Meeting at Holly wood, Calif. 
**Dept. of Physics, Massachusetts Institute of Technology. 



The essential features of the optical system are shown in Fig. 1, 
The source of light is a "pointolite" lamp, P. The collector lens, L. 
images the globule of the lamp on the substage condenser, SC, which, 
in turn, images the collector lens on the stage of the microscope at 
S. The lenses, and EE, represent the objective and eyepiece of 
the microscope, respectively. This much of the optical system is 
built as a unit, mounted on a board as shown in Fig. 2. It is suf- 

FIG. 1. The optical system of the cine-photomicrographic apparatus. The 
pointolite lamp P illuminates the stage S by means of the collector lens L and 
the substage condenser SC. The microscope objective is at O and the eyepiece 
at EE. The microscope is focused to form at infinity a virtual image which 
is re-imaged on the film F by means of an ordinary camera lens C. A piece 
of plain glass G and the telescope T take the place of the usual searcher eye- 

ficiently rigid to be carried about without materially disturbing the 
adjustments. When several investigators wish to use the same cam- 
era, a number of such units can be constructed at little additional 
expense. Each investigator can then use the microscope with which 
he is already familiar. 

The remainder of the optical system consists of an ordinary motion 
picture camera objective, C, located so that it forms an image of an 
infinitely distant object on the film at F. In front of the camera lens 

218 A. C. HARDY AND O. W. PINEO [J. S. M. P. E. 

is a piece of plane glass, G, which acts as a beam-splitter. Some of 
the light is directed into the searcher eyepiece, T, which is, in effect, 
a low-power astronomical telescope containing the reticule, M, in 
the focal plane of the objective. When the microscope is focused 
to form an infinitely distant virtual image of the object on the stage, 
this image will be re-focused by the telescope in the plane of M. 
Since the camera lens C is permanently focused in its "infinity" posi- 
tion, the image will also be sharply focused on the film. The reticule 
is preferably ruled to indicate the limits of the field that can be photo- 
graphed and the limits of any stops that may be placed in the camera. 
It enables the operator to keep the objects of interest near the center 
of the field as well as to maintain the focus of moving objects. 

FIG. 2. A photograph of the microscope and accessory apparatus. The 
light source and microscope are mounted together on a baseboard so that 
the microscope can be used visually in the ordinary manner until a few 
moments before beginning the exposure. 

The camera with its drive and timing mechanism is mounted on a 
track secured to the wall in such a manner that its height can be 
varied several inches by means of a screw ending in a crank, as shown 
in Fig. 3. The baseboard containing the microscope and illuminating 
system is supported on a table beneath the camera. The procedure 
which is followed in using this apparatus is first to remove the base- 
board assembly to a convenient location while the subject on the stage 
is prepared for photographing. This part of the procedure usually 
consumes the most time. The advantage of being able to use the 
microscope independently of the camera is obvious. When the sub- 
ject is ready to be photographed, the baseboard is placed on the table 


under the camera, the height of which has previously been adjusted 
to suit the particular microscope. It is unnecessary to locate tlu- 
microscope accurately with respect to the camera, any position being 
satisfactory that allows the light to enter the camera lens. The final 
focusing adjustment is made by looking into the searcher eyepiece. 
Usually in cine-photomicrography, the lens, C, is omitted and the 
microscope is used for forming the real image on the film. A dis- 
advantage of this method is that the adjustment of the microscope 

FIG. 3. A photograph of the microscope and camera assembled for 
photographing. The driving and timing mechanisms are shown at the 
side of the camera. 

is very different for photographing than for visual use. To obtain 
the required real image for photographing, the correct procedure is 
to extend the draw tube until the eyepiece forms a real image of the 
image formed by the objective.* This adjustment is not simple and 
usually results in making the apparent magnification of the projected 
picture different from the apparent magnification of the visually used 
microscope. With the method described above, the adjustment of 

* Although the same result is obtained by changing the focusing adjustment, 
this procedure is undesirable because objectives are corrected for a single working 

i2:2i) A. C. HARDY AND O. W. PINEO [J. s. M. p. E. 

the microscope is the same when arranged for photographing as when 
used visually. By choosing the focal length of the camera lens prop- 
erly, the apparent magnification of the projected picture is the same 
as that of the microscope. Let us assume an observer is seated in the 
audience at a distance d from the screen. If /i is the focal length of 
the camera lens, C, and/ 2 is the focal length of the lens used to project 
the picture, the apparent magnification of the projected picture is 
the same as that of the microscope when 

where D is the distance from the projector to the screen. A common 
value for fz is five inches, so if f\ is two inches, the magnification rela- 
tionship is correct for an observer seated near the center of the audi- 
torium. The advantage of being able to see the object under the 
proper magnification until a few moments before exposing is not fully 
appreciated without trying it. For the investigator having a limited 
amount of experience in the technic of cine-photomicrography, the 
fact that the projected picture always looks exactly like the view 
seen through the microscope furnishes the confidence that is necessary 
for obtaining uniformly satisfactory results. 

Another important advantage of the method lies in the simplicity 
of the precautions that are necessary to avoid the effects of vibration. 
With optical systems in which the microscope forms an image on the 
film, vibration of the microscope with respect to the camera results 
in an equal displacement of the image on the film. If an attempt is 
made to prevent this by a rigid mechanical coupling between the 
microscope and camera, the driving mechanism sets the stage into 
vibration, an effect which is magnified on the film by the total power 
of the microscope. By causing the latter to form a virtual image at 
infinity, no ordinary amount of motion, either parallel or perpen- 
dicular to the microscope axis, will cause a displacement of the image 
on the film. According to actual test, the microscope can be dis- 
placed as much as one-quarter of an inch in either direction without 
causing the image to move perceptibly on the film or to go out of 

The most serious disadvantage of the system is the extra amount of 
glass that it contains. This reduces the light available for exposure 
by about 30 per cent and causes a very slight decrease in the maxi- 
mum contrast. However, these disadvantages are much more than 
compensated for by the confidence that the simplicity of the system 


gives to the investigator, particularly to those possessing only a 
slight familiarity with the technic of photomicrography. 


The camera is driven by a motor through a set of change gears 
giving seven speeds, from twice normal speed to that at which one 
minute on the screen represents one hour under the microscope. 
Additional gearing for slower speeds would be cumbersome and in- 
convenient because of the very long periods of exposure at very slow 
speeds. This is avoided by using in the gear train a magnetically 
operated clutch which turns the "trick spindle" through one com- 
plete revolution at intervals determined by a timing mechanism. The 
timing mechanism consists of a master commutator of the drum type 
which rotates at a constant speed. Alternate segments are connected 
to an auxiliary commutator within the camera in the same manner 
as in the familiar three-way circuits used to control lights from either 
of two points. When the brush on the master commutator makes 
contact with one of the segments, a current is caused to flow through 
the clutch until the circuit is broken by the auxiliary commutator 
after the trick spindle has turned through a complete revolution. 
The clutch then remains inoperative until the brush on the master 
commutator makes contact with the next segment, when the opera- 
tion is repeated. The interval between exposures is determined by 
the number of segments on the master commutator. In the ap- 
paratus as constructed, nine groups of commutator segments were 
arranged to provide for speeds which permit one minute on the screen 
to represent from fifteen minutes to six days under the microscope. 

The magnetic clutch is operated directly from the 110- volt circuit, 
and consumes about 2 l / 2 watts. It exerts a pull of about twenty- 
five pounds across an air-gap of one millimeter between the coil 
and the armature, and yet does not become appreciably warm if 
accidently left on indefinitely. A spring is arranged to force the 
armature against a braking surface when the current is cut off. Since 
the voltage is applied to the clutch only during the exposure of the 
film, the same voltage supply can be used for other purposes such as 
for turning on the exposing light during the time of exposure or, in the 
case of an arc source, for actuating a magnetic shutter between the 
microscope and the source. This is necessary when photographing 
certain subjects such as molds, which will not grow if illuminated 



When photographing at the higher speeds where the timing mecha- 
nism is not used, the camera is started and stopped by means of 
a push button at the end of a long cord which controls the action of 
the clutch. The illumination on the film is adjusted to its proper 
value by means of neutral filters inserted near the collector lens, C 
(Fig. 1). In making test exposures for determining the proper filter 
to use, it is convenient to be able to expose a single frame at any de- 
sired time. This is done by means of a four-way snap switch which 
cooperates with the commutator within the camera in such a manner 
that the trick spindle is caused to make a complete rotation for each 
snap of the switch. When photographing slow processes with the aid 
of the timing mechanism, it is usually desirable to have a few feet of 
leader showing the appearance of the subject before the action begins. 
In this case, the timing device, having first been adjusted to make 
exposures at the proper intervals, the leader is run off by depressing 
the push button; upon the release of the push button, the timing 
device assumes control for the remainder of the process. 


D. R. WHITE** 

Summary. Curves, photomicrographs, and spectrograms are presented and 
discussed showing sensitometric tests both with incandescent white light and with 
colored lights, rate of development characteristics, and color sensitivity and graininess 
for both du Pont special and du Pont regular panchromatic negatives, 


The general sensitometric characteristics of du Pont regular and 
special panchromatic negative emulsions are shown in Fig. 1 and 
Fig. 2. Fig. 1 is a family of curves representing the rate of de- 
velopment of the special negative and Fig. 2 is a similar group of 
curves for the regular negative. For all of these curves, and in fact 
for all sensitometric data presented in this paper, the light source 
was an incandescent lamp operated at a color temperature of 2475 K. 
so arranged as to give an illumination of five meter-candles on 
the film as exposed in the sensitometer when no filter was interposed 
between the light and the film. The exposures were non-inter- 
mittent and were increased by factor two steps in time from one ex- 
posed area to the next. The sensitometer was of the sector wheel 
type having no unusual design features, and was driven at constant 
speed by a synchronous motor. With the particular wheel speed 
used, the longest exposure was 1.25 second and the shortest was 
0.00122 second. The greatest and the least exposures, expressed 
as the product of time and intensity, were, therefore, 6.25 and 0.0061 
candle-meter-second. These values are shown on the curves by 
their logarithms which are, closely, 0.8 and 3.8, respectively. 

The development was carried out in a borax metol formula. 1 
The developer was highly agitated during the development, a pro- 
cedure which tends toward reproducibility of results but which also 
tends toward higher gammas at the shorter times of development 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Du Pont-Pathe Film Mf. Co.. Parlin, N. J. 




[J. S. M. P. E. 








Source'. Incandescent Lamp 
Color Temperature 

247 5 K. 

2 .01 

Log (It) C.M.S. 

5.8 2.1 ~24 2.7 1.0 /.J 1-6 /.? -2. .* 

FIG. 1. Rate of development curves for duPont special 
panchromatic negative. 

J ' h J)uPotir 

Panchromatic Negative 

Source: Incandescent Lamp 
Color Temperature 
2o\- 2475* K. 


2.1 21 27 10 /J / /? -2 * - 8 

FIG. 2. Rate of development curves for du Pont regular 
panchromatic negative. 

Aug., 1931] 



than would be obtained in some laboratories. Very similar curves 
would be obtained in any other satisfactory negative developer, 
although the time taken to reach any specified gamma would ob- 



3Q 21 *+ 27 /.O J.3 7tf 1.9 .Z SB 

FIG. 3. H and D curves of du Pont panchromatic negatives. 

viously depend upon the developer chosen, the temperature at 

which it was used, and the degree of agitation during development. 

The two families of curves in Fig. 1 and Fig. 2 show that both 





J)cve/opmfn1- T/mt /V//7. 

O 2 -f 6 A M t* * * 

FIG. 4. Time-gamma curve for du Pont panchromatic negatives. 

films are capable of producing gammas somewhat higher than unity, 
thus having potential contrast-giving possibilities beyond the nor- 
mal requirements for negatives produced under present practices. 



[J. S. M. P. E. 

The greater densities produced on the special negative by corre- 
sponding exposures and developments of the two films show the 
greater speed of this special stock. To present this more clearly, 
Fig. 3 shows the curves for 6 minutes' development plotted together. 

The gamma values taken from the curves of Fig. 1 and Fig. 2 
are plotted together against' the time of development in Fig. 4. 
Since the two sets of points fall so close together, only one curve 
was drawn to represent the time-gamma relationship. This curve 
represents the time-gamma relationship for only one developer and 
one set of developing conditions, but no large difference in the time- 
gamma curves for the two stocks is to be expected in any commercial 
negative developer. 


The completeness of the color sensitivity of these two films may 
be seen from the spectrograms shown in Fig. 5. Spectrogram A 
is for the special negative and spectrogram B for the regular film. 
These spectrograms were made on a small Hilger grating spectro- 
graph, using a ribbon filament lamp as the source, with a neutral 
wedge over the slit, and do not readily yield quantitative data as 


FIG. 5. Spectrograms on du Pont special (A) and regular (B) 
panchromatic negatives. 

to speed or contrast values. The source used, an incandescent 
lamp, emphasizes the red end of the spectrum in proportion to its 
importance for photography with sets lighted by incandescent lamps. 
From the point of view of over-all film speed the blue is relatively 
more important and the red relatively less so, when pictures are 
taken in sunlight. 

Further information concerning the color sensitivity of the two 
films may be obtained by a study of the curves shown in Fig. 6. 

Aug., 1931] 



Here the curves marked "White" represent the density vs. log 
relation for the unscreened incandescent lamp, which was operating 
as usual, at a color temperature of 2475K. In this plot, E is ex- 
pressed in arbitrary units as only relative values are of interest 
here. The curves marked "Red" represent the results obtained 
when this light was screened with a Wratten A filter. Similarly 
the curves marked "Green" and "Blue" show the data obtained 
with the B and C filters, respectively. It is interesting to note that 
the red filter transmits 40 to 45 per cent of the light photographi- 




FIG. 6. 




/?./ J.O 

0.9 i.z /.<r /a 

H & D curves on du Pont panchromatic negatives, ex- 
posed to light as indicated below. 

White: unscreened incandescent lamp operating at color tempera- 
ture of 2475 K.; red: screened by Wratten A filter; green: screened 
by Wratten B filter; blue: screened by Wratten C filter. 

cally effective on either stock, while the green filter transmits only 
about 9 per cent and the blue filter about 5 per cent of such effective 
light. Of course, it must be borne in mind that these filters are not 
equally transparent at their points of maximum transmission, but 
these data serve to emphasize the importance of the red in photog- 
raphy with incandescent lamps. The fact that all four pairs of curves 
labeled White, Red, Green, and Blue, respectively, have the same 
separation between the numbers of the pairs shows that the relative 
color sensitivity of the two films is the same. The spectrograms of 

228 D. R. WHITE [j. s. M. P. E. 

Fig. 5 indicated qualitatively this fact which now appears quan- 

The filter factors for these films were determined by independent 
experiments and confirm the conclusion just drawn. These filter 
factors, for sunlight, are given in Table I. It should always be 


Filter factors for the Wratten filters, designated by letter, for sunlit scenes, for both 
du Pont special and regular panchromatic negatives. 

Filter Filter Factor 

Kj 2.2 

K 2 3.1 

K 3 4 

G 5 

F 10 
A 7 

B 16 

C 12 

borne in mind when considering such factors that the specification 
of the source is as necessary as the specification of the filter and the 
film. Hence, these values cannot be considered as highly precise 
since the specification "sunlight" itself is rather indefinite. How- 
ever, experience has indicated that these factors are quite satisfac- 
tory for these films under normal sunlight conditions. 


Photomicrographs of the individual grains in these emulsions 
are shown in Fig. 7. Fig. 7 A is a photograph of the grains of the 
special emulsion and Fig. 7B of the regular emulsion. Both photo- 
graphs were taken at the same magnification. Since it is not the 
individual grains but, in general, clumps of grains that produce the 
graininess of pictures as viewed on the screen, the curve of Fig. 8 
is of more value than the photomicrographs in comparing the two 
emulsions. The unit of graininess is arbitrary, but if some standard 
is chosen relative values may be determined. Various instruments 
have been constructed to make such determinations. The results 
presented were obtained with an instrument designed by Conklin. 2 
No significant difference in graininess appears between the two 
films, although the graininess of both is a function of the density, 
as appears from the curve. 

Aug., 1931] 



Closely allied with the graininess of the emulsion is its resolving 
power. This was determined for both emulsions by photographing 

<r -%v & *i-- 

t, S\ <1* ** ' 


A B 

FIG. 7. Photomicrographs of the silver halide grains of 
du Pont special (A) and regular (B) panchromatic negatives. 

a test object consisting of groups of parallel lines. This object 
showed great contrast between its dense and transparent portions. 






Arbitrary i/n/fc 



3pecial O 
Regu/at X 

O.S *0 /f 

FIG. 8. Density-graininess relation for both du Pont panchromatic 

The development of the negatives was carried to a gamma of 0.8. 
Under these conditions the special and the regular negatives both 
resolved 38 to 41 lines per mm. 


1 MOYSE, H. W. f AND WHITE, D. R.: Trans. Soc. Mot. Pict. Eng. t TOIL (May, 
1929), No. 38, p. 445. 

2 CONKLIN, O. E.: /. Soc. Mot. Pict. Eng., XVI (February, 1931), p. 159. 


W. V. D. KELLEY** 

Summary. This paper describes two old and much used color processes. In 
both of these the colors are applied as tints to the black-and-white prints. Hand- 
schiegl used the imbibition method and Pathechrome the stencil system. Both 
systems have been used to produce release prints in commercial quantities. 

As worked by Handschiegl, his process is not what we usually 
term a natural color process. The most successful use for his system 
is in applying tints of color to the customers' own make of black- 
and-white prints. Good scenic prints and excellent work on titles 
are produced, but the method is most frequently used for giving 
"spotting" effects, such as in showing a red cross on the side of an 
ambulance, Will Rogers blushing in The Connecticut Yankee, or in 
fire scenes, which are also well adapted for coloring by this system. 

In nearly every instance the customer furnishes the prints in the 
customary black-and-white stage. The color is applied mechanically, 
differing in this respect from hand coloring methods. The color 
tints, when blended, produce very beautiful effects. 

Handschiegl started in the photoengraving and lithographic 
business and was very skilful at blending colors and producing 
satisfactory matrices. As this skill was largely individual, it died 
with him. The making of the master positive, from which the 
matrices were made, received Handschiegl's personal attention. 
They are obtained by printing back and forth until the parts to be 
colored stand out from the balance of the picture. The next step 
is the "blocking out" process, done by hand. This consists in paint- 
ing out the parts not wanted or in shading those that are needed. 
From this master, the prints or matrices are made. The matrix 
print is developed in the usual way, then bleached in a bath that 
hardens the gelatin surrounding the silver particles, leaving the 

* Presented in the Symposium on Color at the Spring, 1931, Meeting at 
Hollywood, Calif. 

** Duchrome Film System, Hollywood, Calif. 


clear portions soft as is possible. The bleached print is then im- 
mersed in a saturated solution of the dye in water, say, about two 
pounds of dry dye to five gallons of water, is next passed through 
blowers or wipers for removing surplus dyes and finally to a drying 
set of rollers. From such a matrix about two impressions of the 
same density are made and the matrix is again dyed. The life of 

FIG. 1. Pathechrome stencil cutting machine. 

the matrix is 40 runs. The dyes used are acid dyes and not espe- 
cially of Pinatype nature. 

The machines for imbibing" the dyes have -three impression 
drums of about 12 inches in diameter with sprocket teeth that are 
not full fitting. Each machine has three drums, enough to use 
three colors in one passage through the machine. At each of the 
three drums provision is made for drying the matrix while the 



[J. S. M. P. E. 

positive continues over two or three of the impression wheels, ac- 
cording to the number of color tints required. The positive re- 
ceiving the impressions passes from one color to the next, all three 
colors being applied one over the other and the blank is not dried 
until finished. 
At the start of operations the positive which is to receive the 

FIG. 2. Pathechrome coloring machine. 

colors is fed through damping means consisting of water and oxgall, 
receiving considerable wetting. Just before the two films are fed 
to the impression drum, emulsion to emulsion, each film is fed over 
a train of sprocket wheels designed to give tension for longitudinal 
registration, while lateral registration is attained from the adjustable 
lateral positions given the sprocket wheels. Discrepancies that 
might occur in registration are negligible, due to the color tints 


being imbibed on black silver prints which tends to hide the faulty 

Attempts were made to apply color from color-selective negatives 
using this system. A black-and-white print was made from the 
negatives taken with a red filter. To this print were applied two 
complementary colors by means of matrices made from positives 
of each of the original two-color negatives. This produced some 
very excellent results, the main difficulty being that anything "black" 
in the subject received the greatest quantity of dye from the matrix 
which, when imbibed to the positive print, inclined to splash over 
where it would show the most. 

At the speed of 360 feet an hour these matrices did not produce 
sufficient color on a blank for the transfers to make strong enough 
blacks to be used as prints without the keys, but for tinting, gave 
plenty of color. 

The system is what is generally known as Pinatype. Blacks 
can be produced and the system is capable of making imbibed prints 
on a blank, but Handschiegl did not set up to do this type of work. 

Attempts were made to colortone positive prints one color and 
then apply a complementary color by imbibition. To tone such a 
print it was not found possible to use any known color toning system 
without producing some relief or differential hardness on the surface 
of the print, even when printed to the back. For that reason it 
was not found practicable to make color prints in this way. 

The use of basic dyes for the imbibition work is not wholly suc- 
cessful, the principal fault being lack of smoothness, and acid dyes 
were relied upon. 

The matrices produce some relief in the surface but not as great 
as in the wash-out method. Positive prints of a quality suitable 
for making dupe negatives are the best. These were bleached in a 
bath composed of a copper salt, and bichromate, the latter controlling 
the hardness. 

There is a great similarity in the finished product of Handschiegl 
and that of Pathechrome. Both produce tints applied to positive 
black-and-white silver prints and both call for hand work in the 
preparation of the matrices. Both, also, can use the trained ex- 
perience of lithographers, artists, etc., as many of the colors are pro- 
duced by overlapping the colors and securing blends. 

The Pathechrome matrices are cut by hand and are not at all 
produced by photography. A stencil is made from a celluloid strip, 

2:J4 W. V. D. KELLEY 

one strip for each color, on a pantograph device which has a vibrating, 
electrically driven needle that cuts the celluloid away completely 
in the stencil film. The stencil film is carried under the electric 
needle while a companion picture film is carried in synchronism 
with it and projected up to about lantern size, over which the long 
end of the pantograph arm swings. An object to be traced is followed 
over the enlarged picture and the needle at the opposite end cuts 
away the celluloid in the normal picture. Each picture in a series 
is done in this manner for each of the colors that are to be applied. 

The matrix film is then a series of openings through which a color 
is applied to the finished print. The celluloid to be cut for the stencil 
is a positive print from which the emulsion is later removed and the 
film cleaned. The show prints are made on a registering printer 
in which the feeding pins, in a step movement, draw both the negative 
and positive forward one frame at a time. About midway of the 
stroke, one of the feeding pins spreads sideways from the other, thus 
adjusting the films laterally. The prints are sometimes toned to 
produce one of the shades to be used. 

In the Handschiegl process a photograph reproduces the matrix, 
while in the Pathe* chrome process a stencil cut by hand does the work. 
In both cases, each frame is worked by hand, for in the Handschiegl 
method all parts not wanted are blocked out with color, by hand. 

Coloring by Pathechrome is much more rapid than by imbibition. 
The stencil and positive to be colored are brought into contact over a 
sprocket wheel while a velvet ribbon wipes a color through the 
stencil to the positive. This color ribbon is a loop of about one 
foot in diameter. A series of brushes feeds the dye to the ribbon, 
so that it does not receive too much of the colored liquid. The 
film passes through this machine at the rate of about 60 feet per 



F. P. BRACKET"!** 

Summary. The application of sound picture technic toward the solution of solar 
eclipse problems is described. Motion pictures of the shadow spot cast upon the earth 
by the moon during an eclipse are taken simultaneously with photographic records of 
time signals broadcast by radio. By coordinating the information contained in these 
photographic records of the shadow spot, the time signals, and identification marks 
on the earth, sufficient information is available for solving various astronomical prob- 
lems such as determining with greater accuracy the distance of the moon from the 
earth, the relative positions of earth, moon, and sun, and to permit more accurate 
computation and prediction of eclipses. A method is also described of making a 
qualitative study of the variation of light intensity at points in the path of the shadow. 

In all the strange and beautiful phenomena of nature, I suppose 
there is nothing as thrilling and spectacular as a total eclipse of the 
sun; and yet, strange to say, very few really successful motion pic- 
tures of a solar eclipse have been made. 

This is probably due to the fact that motion picture men and 
astronomers did not cooperate in the effort until within the last two 
or three years. Several attempts to obtain such pictures failed be- 
cause the cameraman did not follow the counsel of astronomers in 
meeting conditions entirely different from those with which they were 
acquainted. On the other hand, astronomers, with all their experi- 
ence in photographing celestial objects of all sorts, could not make 
a motion picture of a solar eclipse without the assistance of experienced 
motion picture men and their instruments. 

In 1923, astronomers flocked to California to observe a solar eclipse. 
In organizing an expedition from Pomona College, we conceived the 
idea of taking motion pictures which would furnish a complete graphic 
record of the eclipse for scientific study, and at the same time be of 
popular and commercial value as a motion picture. A scenario was 
written which included all the dramatic features incident to the 

* Presented at the Spring, 1931, Meeting, at Hollywood, Calif. 
** Pomona College, Claremont, Calif. 


236 F. P. BRACKETT [j. s. M. p. E. 

preparations, the voyage to the station, and the activities of the 
observers during the eclipse, as well as views of the eclipse itself. An 
agreement was made with a motion picture company to "shoot" the 
pictures. When the time came, however, they decided "to go it 
alone," with the result that neither they nor we got the motion pic- 
ture, though other parts of our work were successfully done. 

During the past two or three years a number of good cinema-eclipse 
pictures have been made, one of them, by the way, on a winter morn- 
ing in New York. In every instance this has been accomplished by 
the earnest cooperation of producers and astronomers. I believe 
that we have only started on the road to success in this field. 

A total solar eclipse occurs when the moon intervenes between the 
earth and the sun, and its shadow falls upon the earth. From any 
point in the shadowed area of the earth, one sees the sun covered by 
the black disk of the moon, its light being blotted out. But if one 
were looking down upon the earth from the moon, he would see a dark 
oval-shaped shadow moving rapidly across the earth's surface. 

If the shadow-spot were small enough he might even see it all 
from the summit of a high mountain or from an aeroplane. Accord- 
ingly, Dr. Whitney and I organized another expedition from Pomona 
College, at the time of the total solar eclipse in April, 1930, to obtain 
motion pictures of this shadow of the moon upon the earth from an 
aeroplane, and to locate the shadow and time its motion with the 
greatest possible accuracy. 

The result of this undertaking, if successful, would be that we 
should be able, by locating and timing the shadow, to determine 
with new accuracy the moon's distance from the earth, and so the 
relative positions of earth, moon, and sun; and hence, among other 
things of much importance, to permit more accurate computation and 
prediction of eclipses. 

Stated thus briefly, the problem looks simple enough, and is easily 
understood; but it proved to be a quite an undertaking, involving 
hundreds of people and elaborate equipment. 

The eclipse of April 28, 1930, was very unusual, and because of this 
unusual character, it was ideal for our purpose. The eclipse was very 
short, totality lasting only l x /2 seconds (the average duration of a 
total solar eclipse is two or three minutes), which was quite unfavor- 
able for most observations. Its brevity was due to the fact that the 
shadow of the moon, cast by the sun, barely reached the surface of the 
earth, passing over a strip of a few hundred miles, and the shadow spot 


along this line was very small only 2 /3 of a mile across at its maxi- 

It is a very curious circumstance that the size of the moon and its 
distances from the earth and the sun should be in just such a proportion 
that the length of the moon's shadow (the umbra) very closely 
approximates the distance of the moon from the earth, i. e., about 
240,000 miles. It varies a few thousand miles in length, so that 
sometimes the earth is within the umbra and we see a total eclipse, 
and sometimes it is beyond the umbra (i. e., in the penumbra) 
and the eclipse is annular. It is still more curious and unique when 
these distances are so closely the same that the point of the cone- 
shadow just touches the earth's surface for so short a path and with so 
small a spot. 

Computation indicated that if pictures were taken from a height 
of 12,000 to 15,000 feet above the ground this shadow-spot might be 
entirely contained in the frames of a motion picture with margin 
enough for identification of nearby objects. 

Geometrically, of course, two points are needed to determine a 
straight line. Hence, to locate the central line of the path of totality 
(which for a few hundred miles is nearly straight) we required two 
well separated sets of positions of the shadow. This meant also that 
we required four stations, two on the ground and two in the air, two 
good motion picture cameras, and two powerful aeroplanes. 

This is not the place to tell the long story of preparation the 
preliminary computations, the study of lighting conditions, the 
investigating and testing of films, the securing of aeroplanes and cam- 
eras, the selection of stations, the building and adjustment of auxiliary 
instruments, the transportation to the stations and setting up of the 
instruments, the placing of a large pattern of identification marks 
over miles of desert floor two or three months of intensive work. 

In solving this problem not only the exact location of the shadow 
was needed, but the exact time of the spot-location for each separate 
picture. For this, very fortunately, we were able to use a method 
that would have been quite impossible during previous eclipses 
that is, to use a sound-camera to record time signals on the film itself. 
Hence we had to provide either for an astronomical determination of 
time on the spot or for the broadcasting of time signals by an astro- 
nomical station, and this required a radio receiver in the aeroplane in 
addition to the camera. 

To make a long story short, we established two regular ground 

2oS F. P. BRACKETT [j. s. M. p. E. 

stations one at Ramm's Ranch, near Camptonville on the west side 
of the Sierra Nevada range in Yuba county, Calif., and the other 
nearly 100 miles distant, at Honey Lake, north of Reno, Nev., on the 
east side of the mountains. Motion picture cameras for the graphic 
record of the eclipse itself and other instruments for the more custo- 
mary eclipse observations were set up at these stations. A great 
deal of consideration was given to the matter of landmarks which 
could be identified in the pictures of the shadow. Huge crosses of 
canvas were suggested, and whitewashed areas and buildings, in 
addition to the natural features of the landscape. All these were used 
to some extent, but in the end we relied chiefly on pairs of 25,000 
candle-power flares, suitably placed and set off by alarm clocks. 
By placing these pairs of flares, some parallel to the central line of the 
computed path of the shadow and some perpendicular to it, and 
by spacing them differently in certain patterns, we could identify any 
pair in any frame of the picture. 

Eventually, two large planes, each with two experienced pilots, 
were placed at the service of the expedition. One was a tri-motored 
Fokker cabin plane and the other a large Fairchild army plane. The 
Fokker, assigned to the Ramm's Ranch station, was equipped with a 
first-class motion picture camera, and flew from Mather Field. 

A place on the dry bed of Honey Lake was chosen as the base for 
the army plane. In this plane were installed the sound camera 
with its amplifiers and batteries and the radio receiver. Arrange- 
ments were made with the Navy Department to broadcast time 
signals each second during the period of totality for this region. 

A number of test flights and exposures were necessary so that 
all the complex manoeuvers of observers and instruments could be 
tried out and coordinated, the pilot, for instance, handling the plane 
so that the camera could follow a train on a curved track. All this 
was accomplished from Clover Field where the instruments were 
installed in the army plane under Captain Stevens who commanded 
the plane, and who, being himself a skilled aerial photographer, 
aided the sound camera expert by operating the camera. 

On the day of the eclipse heavy clouds covered both sides of the 
mountains throughout the period of the eclipse. Only through breaks 
in the clouds were glimpses of the pageant seen from the ground. 
From the air, the sight was marvelous indeed. The plane from 
Mather Field, finding clouds over Ramm's Ranch, flew westward over 
the predicted path, as had been planned in case of such a contingency, 


and took pictures of the country below, though not quite sure of the 
shadow, battling with cold and exhaustion at an altitude of 19,000 
feet. Interesting pictures they are, taken through scattered clouds, 
but the shadow of the moon could not be defined in them. 

The flight of Captain Stevens and his two associates in the army 
plane was even more dramatic and, I believe, also historic. The 
story is recorded in Pomona College publications how they waited 
under the clouds, all ready to go, until hardly an hour remained to 
reach the great altitude required; how at last a small clearing ap- 
peared, and they took off, pushing up through this hole, through a 
mile-depth of clouds, and then came out above them; how they 
climbed still higher until they reached 18,500 feet, just in time to 
swing into position as totality began; how they blanketed their 
instruments to keep them warm and themselves to keep from freez- 
ing; how they had to conserve their oxygen supply; how they saw 
the shadow appear in the distance and rush on toward them; how 
they beheld it appalled, not realizing at first what it was; how they 
got their pictures in spite of every difficulty ; and how they came down 
at last, through the clouds, to a safe landing on the dry lake bed a 
thrilling story as told by Captain Stevens and his companion, James 
W. Balsley. 

For the first time in history those men saw the great shadow of 
the moon coming upon them with terrific speed Across the surface 
not of the ground, alas but over the upper surface of the clouds. 
For the first time motion pictures were taken of this phenomenon as 
the shadow came and went. 

Astronomically, of course, we were disappointed that the shadow 
was not seen upon the ground where its exact position could be deter- 
mined, instead of upon the rough and billowy surface of clouds 
where its outline was too vague to be well marked in the film, although 
it may be readily followed on the screen. Great as our disappoint- 
ment was at the time, we know now that, while leaving much to be 
desired, the expedition was far from being a failure, as I shall point 
out in a moment. 

So far I have spoken of one of the two problems in which our ex- 
pedition was chiefly concerned. Let me now, much more briefly, 
refer to the second problem. 

In this we undertook to measure the intensity of the sun's radia- 
tion, especially the intensity of the sunlight itself, at a number of 
points in a line across the path of totality. Five such points some 


500 yards apart were selected at Ramm's Ranch, in a line perpendicu- 
lar to the computed central line. At each point an instrument 
was placed, consisting essentially of a photoelectric cell and amplifier, 
and a milliameter whose index marked the changes in intensity of 
light as the shadow passed over the point during the partial and total 
phases of the eclipse. All these milliameters, each connected by long 
lines to its distant photometer, were mounted upon a panel at a cen- 
tral station together with two timepieces, so that all these ammeter 
dials and clock faces could be photographed simultaneously by a 
motion picture camera by two of them, in fact. In this way a 
continuous picture was taken showing the variation in light intensity 
at each point, and graphs were plotted for each point. The net of 
these curves, then, not only locates the path of totality, but tells 
much more as to the intensity of the radiation and illumination. 
At the national meeting of the A. A. A. S. in Chicago, last August, 
where the work of this expedition was reported to the Astronomical 
Section, it was agreed that two things were accomplished that were 
quite worth while. The solution of two entirely new problems had 
been undertaken. In both cases a new technic was proposed and 
tried out, establishing a new method which might be tried again with 
good hope of success even though the conditions would not be so favor- 
able again for perhaps a hundred years. Already we are considering 
a repetition of the* experiment with the eclipse of August, 1932, in 
New England. 



It is a pleasure to welcome you to this, the thirty-first convention 
of the Society. Our twenty-fifth convention was also held in Holly- 
wood. Although that was only three years ago, by comparing our 
status then and now, we can realize how our Society has grown not 
only in size but in its value to the industry and the world at large. 
The comparison also emphasizes the magnitude of the changes that 
have occurred in the technic of producing motion pictures. 

In 1927, the tools of production consisted largely of cameras using 
orthochromatic film and arc lamps. The year following, panchro- 
matic film was introduced and was soon universally adopted. As a 
consequence of the improvement in photographic quality which re- 
sulted, the producers began to direct more attention to the technician 
because they saw that he is also a potential contributor to box-office 

A study of the relative merits of arc and tungsten lamps for lighting 
sets was next instigated by the American Society of Cinematographers 
and the Academy of Motion Picture Arts and Sciences, and these 
experiments were concluded just prior to the Hollywood convention. 
The use of sound in conjunction with the motion picture was begin- 
ning to be discussed, but with many misgivings. Our Society staged 
the first demonstration of Photophone equipment in Hollywood, 
although the demonstration attracted but slight attention from the 
producers. Six months later the sound revolution commenced; 
there followed a mad scramble to build new stages and modify old 
ones, and in a relatively short time there was on the influx of a large 
army of skilled technicians to take care of the new equipment and 
procedure. In the short space of three years remarkable advances 
have been made in the technic of recording sound and in the making of 
motion pictures, and it is therefore fitting that we should hold our 
national convention in this center of production in order to exchange 
ideas and discuss our new problems and recent researches. 



A wide gap of 3000 miles between the technicians in the East 
and those in the West, and an economic depression are, of course, not 
conducive to frequent meetings in Hollywood but I think it is highly 
important that the time intervals between our conventions in Holly- 
wood should not exceed two years. 

During the past six months our Society has undoubtedly made 
more progress than in any similar period of its existence. In Janu- 
ary, 1930, an important milestone was passed when the form of 
publication of our technical papers was changed from the quarterly 
Transactions to the monthly JOURNAL. 

A second milestone was passed in November, 1930, when our 
Society acquired an Editor-Manager and permanent headquarters 
at 33 West 42nd Street, New York, N. Y. The Editor-Manager, Mr. 
Sylvan Harris, is a graduate electrical engineer with extensive re- 
search and editorial experience and, in addition to editing the JOURNAL, 
has taken charge of much of the routine business formerly undertaken 
by the Secretary and committee chairmen. 

Our Society has continued to disseminate an increasing amount 
of technical information through the medium of the JOURNAL. The 
quality and quantity of the technical papers has been maintained and 
an increasing proportion of these have dealt with fundamental 
principles which are so vitally necessary for the healthy advancement 
of the industry. Several new sections have been added, including 
those devoted to Patent Abstracts, Committee Activities, and Activi- 
ties of the Academy. The readers have also been kept in touch with 
developments in foreign countries by means of translations of articles 
originally published in French, German, and Russian. The section 
devoted to abstracts of technical papers has been enlarged, due to the 
establishment of an organized staff of abstractors. 

An Open Forum has also been initiated, through the medium of 
which readers may offer suggestions relating to the welfare of the 
Society, draw attention to problems requiring investigation, or 
make preliminary announcements of their technical discoveries. 

The circulation of the JOURNAL numbers about 1000 which is some- 
what unsatisfactory. It is hoped that it will be possible to reduce 
the subscription price in the near future to permit of much more 
widespread circulation which it deserves. 

The sections of the Society, having their headquarters in New York, 
Chicago, and Hollywood, have been increasingly active and have held 
local meetings at regular intervals, thereby drawing attention to new 


problems and developments with a minimum loss of time and permit- 
ting more intimate discussion than is usually possible at the semi- 
annual meetings of the Society. 

It was with extreme regret that the Board of Governors resolved to 
disband the London Section. Refusal of the Board to accede to re- 
quests for reduced entrance fees, authority of this section to appoint 
Active members, and a non-budgeted expense account resulted in the 
resignation of the officers of the section, who, in turn, established 
the independent British Kinematographic Society. Fifty of the 
members of the London Section retained their membership in our 
Society. We wish the new Society every success and will collaborate 
to the fullest extent on technical matters. 

The various standing committees have worked untiringly and with 
regularity, as contrasted with the somewhat spasmodic efforts of 
many previous committees. The members of the Progress Com- 
mittee are distributed throughout the world, and their submitted 
reports result in making the Progress Report a representative picture 
of world developments. The fine papers program before you is the 
result of organized solicitation by the Papers Committee, which has 
been successful in securing advance abstracts of all the papers for 
publicity purposes. The Standards Committee has finally arrived at 
a recommended standard for wide film and has prepared a glossary 
of motion picture terminology which will be published in an early 
issue of the JOURNAL. 

The excellent arrangements for the present Convention are an in- 
dication of the efforts of the Convention Committee. The Publicity 
Committee has consistently secured excellent trade notices, while 
through the efforts of the Color and Paper Committees, it has been 
possible to arrange for the color symposium during this Convention. 

The Historical Committee has published papers in the JOURNAL 
dealing with the achievements of pioneers in the industry and has ar- 
ranged for an exhibit of historical apparatus for the present convention. 
Members are urged to donate apparatus of historical interest, which 
will be placed permanently on exhibition in a suitable depository. 

Four new committees have been appointed, dealing with Projection 
Practice, Projection Theory, Projection Screens, and Sound. The Pro- 
jection Practice Committee has set an example for other committees to 
follow by establishing regular bi-monthly meetings and its delibera- 
tions have resulted in recommendations for standard layouts for projec- 
tion rooms, improved projector design, and remote control of volume. 


The Projection Screens Committee is endeavoring to acquire suffi- 
cient data to permit a recommendation for a standard of screen 
brightness, and the Sound Committee is assembling information on 
ways of improving methods of sound recording and reproducing. 
Other committees in the process of formation will deal with laboratory 
practice and studio practice and it is proposed to appoint separate 
subcommittees on both the east and west coasts to deal with these 

It is through the committees that the Society can best serve 
the industry in the capacity of a coordinating and cooperating 
medium. Committee work can take the form of (a) reports on 
progress, (b) the formulation of standards, and (c) a discussion of new 
problems. It appears to be an open question as to whether or not 
committees should undertake to perform research work but when this 
is possible without entering into comparisons of competitive mate- 
rials, it is very desirable and is to be encouraged. 

The past six months have also been made conspicious by the in- 
creased activity of the Society in collaborating with other organiza- 
tions and societies having interests related to our own. Our Society 
has acquired membership in the American Standards Association, 
which has recognized the various standards adopted by the Society, 
and also in the National Fire Protection Association, which has 
invited the Society to collaborate with regard to safety measures in 
the handling of nitrocellulose film. Contacts have been made with 
the Institute of Architects with a view to collaborating in the design 
of theaters, particularly with regard to projection and acoustical 

The Society will be officially represented at the 1931 International 
Congress of Photography in Dresden and arrangements for the ex- 
change of technical manuscripts have been made with the Deutsche 
Kinotechnische Gesellschaft, which has conferred Honorary Member- 
ship upon the Presidency of our Society. The Society was also rep- 
resented officially at the Inter-Society Council on Color Specifica- 
tions, sponsored by the Optical Society of America. 

In conclusion, I wish to thank the secretary and treasurer, the 
various committee chairmen, the members of the Board who have 
given unsparingly of their time and energy, and all those who have 
labored in the interests of the Society. 

J. I. CRABTREE, Preside! 


: ; 




The following recommendations have been adopted, after an 
exhaustive study, by the entire committee and are submitted for 
adoption as standards. In following them the local code should 
in all cases be consulted for deviations from these standards. It is 
the aim of the Committee to bring them before the various agencies 
for revision and adoption. Three layouts have been adopted, 
marked A, B, and C, which were planned for flexibility, simplified 
construction, ease of operation, etc., to be selected according to 
the size of theater and type of operation. The key to the symbols 
used on the plans is shown in Fig. 1, and the three plans are shown 
in Figs. 2, 3, and 4. 

(1) Projector Spacing. The distance between projectors shall 
be not less than 4 l / 2 feet nor more than 5 feet, measured between 
lens centers; for projection distances less than 100 feet, the spacing 
shall be 4 feet. When two projectors are used, they shall be equally 
spaced on either side of the center line of the auditorium. When 
three projectors are used, the center projector shall be placed on the 
center line of the auditorium. 

(2) Observation Ports. Observation ports shall be 12 inches 
wide and 14 inches high and the distance from the floor to the bottom 
of the openings shall be 48 inches. The bottom of the opening 
shall be splayed 15 degrees downward. In cases where the thickness 
of the projection room wall exceeds 12 inches, each side shall be 
splayed 15 degrees. 

(3) Projector Ports. Projector ports shall be 10 inches wide 
and 12 inches high (see Fig. 5). The bottom and sides of the open- 
ings shall be splayed in the same manner as observation ports. The 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 



distance from the floor to the bottom of the openings shall be in 
accordance with the table of projection angles as given in the ac- 
companying plans for the layout of the projection room. 

(4) Other Openings. All other openings, such as those intended 
for effect projectors, double dissolvers or single spot lamps shall be 
24 inches wide and 34 inches high. The distance from the floor to 
the bottom of the openings shall be 26 inches when the angle of 
projection is not greater than 20 degrees. For projection angles 
greater than 20 degrees, one inch shall be deducted from this value 
for each degree in excess of 20. The minimum spacing allowed 
between these openings shall be as shown on the plans for the pro- 
jection room layout. The placing of these openings to the right 
or left of the projectors shall be optional and according to conditions. 

(5) Dimensions of Projection Room. The projection room shall 
have a minimum height of 10 feet and a maximum of 12 feet. The 
minimum depth of the room shall be 12 feet. The length of the 
projection room shall be governed by the amount and type of equip- 
ment, as shown on the plans. Consideration should always be given 
for probable future needs. 

(6) Front Wall. In all cases, the inside surface of the front 
wall of the projection room shall be smooth and without structural 
projections. Care shall be exercised in locating the hanging rods 
and columns in the front wall so as not to interfere with the proper 
location of the various openings. 

(7) Conduits. These shall in all cases be concealed, and all 
boxes shall be of the flush-mounting type. 

(8) Projection Arc Conduit. The size of conduits for projection 
arcs shall be as indicated on the plans. These sizes anticipate the 
need for future increased capacity, and should be adhered to in 
order to provide space for pulling in larger wires as needed. 

(9) Conduit for Sound Equipment. Conduit for sound equip- 
ment shall conform with the type of sound equipment to be installed. 
The manufacturers of such equipment should be consulted with 
regard to the proper layout of the sound system before proceeding 
with the installation. 

(10) Projection Room Lighting. An individual ceiling fixture 
with canopy switch shall be installed for each piece of equipment, 
and shall be placed in line parallel to the front wall at a distance 
not less than 18 inches or more than 24 inches from the front wall. 
The outlet connected to the emergency lighting system shall be 


located in the ceiling midway between the extreme ends of the pro- 
jection room, and 4 feet from the back wall. Small projection rooms 
shall be equipped with one reel light and large projection rooms 
with 2 such lights conveniently located. 

(11) Ventilation. A separate exhaust system of ample capacity 
shall be provided for the projection room and other adjacent rooms 
provided for projection equipment. All projection arcs, and arcs 
of other equipment as required, shall be connected into the ducts 
of the exhaust system, which should contain a blower type exhaust 
fan. There should also be a gravity vent in the main projection 
room, rheostat room, generator room, and sound equipment room, 
leading directly through the roof. The minimum size shall be 12 by 
18 inches, maximum size 18 by 24 inches. They shall also be 
equipped with swivel cowls. A supply of fresh air shall be brought 
into the projection room, preferably at the floor level and at the 
extreme ends of the room, and shall be baffled to prevent direct 
drafts. In cases where the theater is equipped with a refrigerating 
system, the projection room system should be connected into the 
main duct of this system. A fan shall be provided of sufficient 
capacity to remove all smoke and gas in case of fire, and this fan 
should be so connected to the port shutter controls that its full 
capacity will be automatically made available upon dropping of the 

(12) Extra Rooms. A separate room shall be provided solely 
for the rheostat equipment. This room shall be provided with 
ventilating means as previously set forth. An additional and 
separate room, properly ventilated, shall be provided for the sound 

(13) Toilet and Wash Room. Hot and cold water and other 
toilet facilities shall be installed and located convenient to the pro- 
jection room. Suitable space shall also be provided for clothes lockers. 

(14) D-C. Supply for Arcs. Two generators or other sources 
of direct current shall be installed to insure continuous operation 
in case of breakdown. 

(15) Location of Arc Generators. Arc generators may be located 
in a room adjacent to the projection room, and the responsibility 
for their maintenance delegated to a projectionist. Where the 
generators are large, making it necessary to reenforce the structure 
carrying them, they may be placed in the basement, provided proper 
maintenance is assured. Where the generators are placed near the 


projection room, this room shall be sound-proofed and the foundation 
for the generator arranged to thoroughly eliminate the noise and 
vibration of the generator. 

(16) Projection Port Shutters. (See Fig. 5.) These shall be 
constructed of not less than 16 gauge iron guides built up of iron 
flats, 2 inches wide and Vs inch thick, with spacers 1 inch wide 
and l /4 inch thick for the shutter to slide in. The shutter shall be 
made of not less than 10 gauge iron, provided with leather bumpers 
on sill at the bottom to take up the shock when the shutter drops. 
Each port shutter shall be connected to a master rod by a string and 
ring attached to a pin on a master rod. The master rod is to be 
fastened securely to the front wall, approximately 18 inches below 
the ceiling. It should be provided with a sufficient number of 
bearings properly aligned to assure smooth operation, connected 
through pulleys and fusible links located over each projector and 
capable of being controlled at the exit so that it may instantly be 
tripped. All large openings in addition to the above shall be pro- 
vided with an individual approved counterweight (see Fig. 6) which 
will permit the shutters to be easily opened and shall be controlled 
by the master rod. All observation ports shall be provided wth 
metal guides to receive V 4 -inch clear glass, this glass to be at an 
angle opposite to the projection angle and arranged to be easily 
removed for cleaning. 

(17) Projection Room Painting. A sufficient number of coats of 
paint shall be applied to assure a good coverage. Walls and doors 
shall be painted an olive green to the height of the door line. The 
walls above this line and the ceiling shall be painted buff. All 
painted surfaces shall be stippled to prevent reflections. All iron 
work on projection ports shall be covered with 2 coats of flat black 
paint. All other rooms shall be painted buff. 

(18) Projection Room Floor Covering. The floor of the projection 
room shall be covered with a good grade of "battleship" linoleum 
(brown or green) or rubber tile securely glued down. The floor 
covering should be laid before the equipment is installed. The 
floors of rooms adjacent to the projection room should be painted 
with a good grade of concrete paint. 

(19) Fire Extinguisher Equipment. The local fire department 
or safety commission should be consulted regarding the proper 
type, amount, and location of fire extinguishing equipment. In 
all cases there shall be adequate provision of such equipment. 










Low Intensity 

30 A. 

No. 4 

Reflector High Intensity 

75 A. 

No. 2 

High Intensity 

125 A. 

No. 00 

Super High Intensity 

200 A. 

200,000 C. M. 

FIG. 1. Key of symbols for projection room layouts. 

36 MINIMUM 2.4" , 3O" 24" 



. o- 



A.C. CAB. 








wore A 


O'TO /O* 




N02-ZSS 3*6 T 



(20) Projection Room Construction, (a) The projection room 
shall be of fire-proof construction, and all walls exposed to the theater 
shall be of tile brick, gypsum, or any approved fire-resisting material. 
The walls of the projection room shall be not less than 6 inches thick 
and shall be covered inside and outside with a layer of plaster at 
least 3 / 4 inch thick. The inside walls and ceiling of the projection 
room shall be coated with an approved sound absorbing plaster. 
Projector ports should be blocked down after the projector is set 
to as small an opening as possible. 

(b) The ceiling shall be of plaster or concrete suspended on 
metal lath, and the floor slab should be not less than 4 inches thick, 
having a 2-inch cinder fill above, and a 2-inch cement finish above the 
cinder fill. 

(c) The walls of rooms adjacent to the projection room shall 
be not less than 4 inches thick, plastered inside and outside. Two 
exits shall be provided, one at each end of the projection room, 
in addition to stairways for entering the projection room. Under 
no circumstances may ladders be used for the projection room en- 

(d) The doors shall be of the approved metal type, swinging 
outwardly from the projection room, and shall be provided with 
door checks or other approved door-closing devices. 

(21) Heating. Proper provisions shall be made for heating 
the projection room. The same facilities used for heating the theater 
should be extended to the projection room. 


This Subcommittee was formed for the purpose of analyzing 
certain difficulties in connection with motion picture projection 
and sound reproducing equipment, and to suggest remedies therefor. 
The difficulties brought to this Subcommittee's attention were as 

(1) inaccessibility of various parts of projectors; 

(2) scratching of film while in transit through the projector; 

(3) oil reaching the film during projection, due to leakage from various parts of 

the projector mechanism; 

(4) difficulty of replacing mechanism when used in connection with sound 

reproducing equipment. 

(1) Inacessibility of Various Parts of the Projectors. This prob- 



lem has been studied somewhat by the Subcommittee, and some 
progress has been made. The Committee hopes to present the 
solution of the problem in the near future. 

(2) Scratching of Film While in Transit through the Projector. 

FIG. 5. Standard projection room port opening. 

rr-rMtSH PLA5T&T - 

FIG. 6. Standard counterweight system for large size projection room port. 


The suggestion was made that the tolerances existing between the 
magazine rollers be increased to such an extent that there is no 
possibility of film coming into contact with metal while passing 
through them. It was pointed out that as a fire prevention measure, 
the laboratories of the National Bureau of Fire Underwriters require 
definite dimensions maintained at these points. They allow sufficient 
leeway, however, so that if the film is not buckled, there is no possi- 
bility of its coming into contact with metal parts excepting at the 
sprocket holes. It was also pointed out that scratching of the film 
may occur when the projectionist allows the film actuating parts 
and film guides to become worn to such an extent that the clearance 
of a few thousandths of an inch is obliterated. It is obvious that 
these parts should be carefully watched and replaced when such 
wear occurs. 

(3) Oil Reaching Film during Projection, Due to Leakage from 
Various Parts of the Projector Mechanism. It was pointed out by the 
manufacturers of projectors that this difficulty was encountered 
only in the old types of equipment, and that improvements have 
been made for eliminating this. One of the worst offending assem- 
blies which causes leakage of oil is the intermittent movement, which 
must normally be kept filled with oil to a certain level. Indicating 
sight gauges are placed in the oil boxes so that the projectionist 
may observe the height of the oil. In the old types of equipment, 
this sight glass was cemented into the casting. In time, the cement 
would disintegrate in places, allowing the oil to seep through. Also, 
in the old type movements, the shafts were designed without pro- 
vision for carrying the oil back into the oil chamber when the bearings 
became slightly worn. These difficulties have been eliminated 
in the newer equipment, and the accompanying illustration shows 
how this has been accomplished. Section B, of Fig. 7, shows a view 
of the intermittent casing and at A are shown the new type oil sight 
glasses. Instead of cementing these glasses, threaded bosses have 
been provided, into which are first placed a washer, then the glass 
and another washer, and the entire assembly is tightened with a 
packing nut. Two such oil sights are provided and leakage at these 
points is entirely eliminated. The leakage of oil from other parts of 
the movement is prevented by felt washers under pressure as shown 
at E and D (Fig. 7). Oil is prevented from seeping through the 
bearing for the star wheel shaft C by a reverse groove cut in this 
shaft, which acts as a pump and carries oil seeping out of the inter- 

Aug., 1931] 



mittent casing back into the case before it can reach the end of the 
bearing. These improvements can be assembled into existing pro- 
jectors using this type of movement. It is only necessary that the 
movements be rebuilt in order to eliminate oil leakage from this 
source. The difficulty of oil leakage was also encountered in prac- 
tically all the other shafts in the old types of projectors, but has 

Srcr/o/y B' 

FIG. 7. Intermittent casing, showing location of oil sight glasses 
and methods of avoiding oil leakage. 

been eliminated in the more modern equipment by cutting a reverse 
spiral curve in these shafts to carry the oil in the opposite direction 
to the side of the projection mechanism into which the film is threaded. 
(4) Difficulty of Replacing Mechanisms When Used in Connection 
with Sound Reproducing Equipment. This has been a very serious 
problem since the introduction of sound reproducing equipment 


but it is mainly encountered in connection with what is known as 
the "D-Spec." attachment. This was the first attachment made, 
and consideration was not given at the time to the varying tolerances 
allowed by the manufacturers of the projector prior to the advent 
of sound film. It was not necessary to machine rough castings to 
which nothing was to be attached when projecting silent pictures, 

FIG. 8. New sound attachment for avoiding shimming. 

but great difficulty was experienced when sound attachments were 
added to these unmachined surfaces. It became necessary to use 
shims varying from one-eighth of an inch to one-thousandth of an 
inch on the several corners of the mechanism in order to properly 
align the projector mechanism with the sound equipment drive. 
Whenever a breakdown occurred during the running of a show, 

Aug., 1931] 



several hours or more were required to adjust the mechanism 
Since the majority of theaters in this country are equipped with 
only 2 sound-equipped projectors, a theater in which such a break- 
down occurred would be left with only one projector to run the show 
until the other projector had been repaired. This, in turn, made 
it impossible to give an up-to-date and smoothly running performance. 
The problem of solving this difficulty was put up to the manu- 
facturers of both sound equipment and projectors, and an attach- 
ment was developed which eliminates the necessity for shimming. 

FIG. 9. New sound attachment dismantled. 

This attachment is quite flexible and by its use the difficulty of 
replacing mechanisms on this old type of sound attachment was 
entirely surmounted, so much so that mechanisms may be readily 
changed within fifteen or twenty minutes. 

Fig. 8 shows the new attachment It is only necessary to remove 
the gear retaining yoke from existing D-Spec. attachments and re- 
place it by the new yoke and idler gears shown in the illustration. 
This yoke is self-centered on the driving spindle for the projector 
mechanism and it is only necessary to insert the spindle in the bearing 


and push it into the hole provided in the mechanism to receive it. 
The yoke is then securely locked on the frame of the sound attachment 
and the bracket carrying the idler gears is then adjusted to eliminate 
lost motion between the gear teeth and the driving unit. The idler 
gear bracket is then securely locked in place by means of lock nut M. 

FIG. 10. Front view of the new sound attachment assembled on 
projector and sound unit without cover and flywheel. 


Fig. 9 shows the assembly dismantled. At A is the flywheel 
which is always provided with the sound attachment; this is readily 
removed by taking out three screws. At B are the lock nut and 
washers for attaching the new yoke to the sound attachment; at C 
are the driving gears connecting the mechanism through the idler 
gears G and H to the main driving gear on the sound unit; at D 
is the spindle which slides into the hole M and upon which the 
assembly C revolves; at E are the three screws for attaching the 
protecting cover L after the unit is assembled; at F is the self- 
aligning yoke which carries the idler gear assembly; at G and // 
are the idler gears; at / is the adjustable bushing to take out end 
play in assembly C; and at K is the adjustable idler gear bracket. 

Fig. 10 shows a front view of the attachment assembled to the 
projector and sound unit without the protecting cover and flywheel. 

No shimming is required with this new attachment regardless 
of the age of the projector on which it is mounted, and it is felt by 
the Committee that this unit satisfactorily solves the problem of 
replacing mechanisms where the old type of sound attachment is 


In the report of the Projection and Sound Reproduction Com- 
mittee, which was presented in abstract before the Society at Wash- 
ington, and in full before the New York Section, June 12, 1930, 
there appeared a section on adjustment of volume levels and remote 
control. This report dealt principally with methods of controlling 
volume directly by an observer in the auditorium. As a matter 
of fact there are now devices on the market which permit such control. 
Whether the use of these devices has proved effective is not clear 
but the fact remains that there is a general urge to investigate fully 
the whole problem of volume control. 

There are three distinct systems for providing volume control 
for theaters: 

(1) the method most generally in use which, to be effective, requires an observer 

in the audience who signals the projectionist for volume change; 

(2) the method described in the above report which provides actual control of 

volume by the observer in the audience ; 

(3) a method which attempts to give to the projectionist some means of knowing 

what volume of sound is present in the auditorium, from which means he 
can adjust the volume from the projection booth. 


Before discussing the advantages and disadvantages of these 
three methods, we may observe: 

(a) The present monitor horn functions reasonably well for the 
purposes for which it was intended, namely, (i) means of checking 
the sound system before the start of a show and (ii) maintaining a 
running check of the system during its operation. 

(b) It seems evident that from a theoretical standpoint the best 
location in which to hear the results obtained in the auditorium 
is in the audience itself. An observer placed in the audience hears 
just what the audience hears, can take into account the audience's 
reaction, and note the effect of the changing number of people, which 
in many houses materially affects the sound absorption, etc. 


System (1) is based on the theory that the actual volume control 
should be handled by the projectionist, and further, that the proper 
place to judge volume is in the auditorium itself. This system, 
therefore, has two most desirable features. The disadvantages are: 

(a) A slight time lag between the giving of a signal by an ob- 
server in the audience and the volume adjustment made by the pro- 

(b) The increased expense of having an observer in the audience. 
(c)' A chance of carelessness on the part of the observer or on the 

part of the projectionist which will result in poor operation. 

(d) The arrangement being described anticipates a rehearsal 
before the opening of the show. With the new release print in vogue, 
the need of such a rehearsal is less since the change-over cues are 
automatically indicated. 

To refute these objections it might be said of (b) that a first-class 
house can well afford such an observer (who would be absolutely 
essential to system (2) which is to be described below), and further- 
more, that a small house which could not afford an observer could 
probably not afford additional monitoring equipment unless it were 
very cheap. Additional equipment requires maintenance and 
usually the cheaper the equipment the greater the maintenance. 

Item (c) anticipates carelessness on the part of the personnel but 
no matter what system is employed carelessness results in a poor 

Item (d) is included under carelessness because if the manager is 
alert a rehearsal should be demanded even if only for sound cues. 



System (2) indicates actual control of volume by the observer 
in the audience. This system has the advantage of reducing time lag 
to a minimum and permits the control to be handled in the audience, 
which is the best position for such observations. The disadvantages 
are again, the additional expense in providing an observer and the 
absolute necessity that this observer must always be present, for 
if he is not, the entire method is not workable. It might further 
be observed that the man in the audience must have knowledge of 
the capabilities of the system itself, otherwise he may overload the 
amplifiers in attempting to override audience noise during periods of 
applause or laughter. The best arrangement of this system calls for 
remote control of the fader because if the audience control is simply 
an auxiliary to the fader in the projection room it produces additional 
loss in the amplifier system which may be disastrous if perchance 
the amplifier system gain is only sufficient to meet normal operating 
conditions. There is, furthermore, a tendency toward split re- 
sponsibility, which is not ideal. 


System (3) anticipates that the projectionist may have some 
means of knowing what is taking place in the auditorium, so that 
he may have entire control of volume adjustments. Any such 
system will obviously be more elaborate and costly than either of 
the other two systems described, and whether it will be more effective 
and usable is doubtful. 

There are several methods proposed to accomplish system (3): 

(a) One system provides a microphone, or several scattered 
microphones, connected to an amplifier and then to a loud speaker 
located in the projection room. 

The advantages are claimed to be that with a microphone in the 
audience the sound from the horns can be picked up and the pro- 
jectionist can then know what sound is being received in the audi- 
torium. In other words, the projectionist's ear has in a sense 
been extended into the auditorium proper. 

It must be remembered, however, that it will be necessary to cali- 
brate very carefully the over-all gain of the amplifier system so that 
the sound in the projection room will definitely indicate whether the 
volume in the house is lower or higher than it should be. If any- 
thing goes wrong with the equipment so that tne over-all gain is 


changed, the results obtained in the monitor horn will not indicate 
the true condition. Furthermore, the microphone will not com- 
pletely reflect the effect caused by the changing number in the 
audience. Any effect from noise in the projection room which 
now hampers good hearing with the present monitor would also 
apply even to a greater extent to the proposed system. 

(b) A second method proposed makes use of a microphone or 
several scattered microphones in the auditorium connected through 
an amplifier into a volume indicator. 

The advantage here would be that a visual indication is presented 
to the projectionist which would not in any way be affected by the 
noise in the projection room. 

There are several disadvantages. To make the system effective 
there should be an optimum point of operation indicated on the 
meter of the volume indicator with maximum and minimum points 
shown, above or below which the sound should never be allowed to 
go. The difficulties in designing such a meter and accompanying 
circuit are extreme. Furthermore, noise picked up from the audience, 
such as laughter or applause, immediately indicates increased volume 
on the meter. In present-day projection rooms, which are fairly 
well sound-proofed, a projectionist might conceivably react in such 
cases by believing that the sound volume through the horns is 
too loud and, as a result, he may reduce the gain of the amplifier 
system when it really should be raised. Again, a very careful cali- 
bration would have to be made in order that the indicator would give 
a reading of true conditions. If any of the constants of the circuit 
should change, an incorrect indication would result, with corre- 
sponding improper sound volume in the house. Likewise in this 
case, as under item (a), the microphone will not definitely take into 
consideration changes in the number of persons in the audience. 

(c) A third method has been suggested, using a headset instead 
of the loud speaker in the projection room. This has such obvious 
disadvantages from an operation standpoint that there is no need 
for discussion. 

It is the opinion of the Committee, that: 

(1) the proper and best place for observance of volume is in 
the auditorium among the audience; 

(2) any manually operated volume control system requires 


that the observer be trained to judge proper volume in the audi- 

(3) there is not at the present time any mechanical or electrical 
device which will give to the projectionists any satisfactory means 
of judging volume; 

(4) with the observer stationed in the auditorium it should be 
recognized that the responsibility of the projectionist in controlling 
volume is only to react to the observer's signals promptly and dili- 

(5) until some other means not now apparent are provided, 
the present system of volume control, as now installed in the ma- 
jority of theaters, is the most satisfactory. This system provides 
signaling means for the use of an observer in the auditorium to 
inform the projectionist when to raise or lower volume and assumes 
a competent observer and painstaking projectionist, which are 
requisites for a good performance in any and all cases; 

(6) it is of the utmost importance that the manager be made 
to realize that the responsibility for obtaining good sound repro- 
duction is primarily his own responsibility. He must provide 
at all times a trained observer, whether it be himself or someone 
appointed for that purpose. He must educate himself to know 
whether the sound system is working properly and that the pro- 
jectionists are responding to the signals of the observer; 

(7) regardless of where the volume control mechanism is oper- 
ated it would be advantageous that the projectionist be able to hear 
what is taking place in the auditorium. It is urged that efforts 
be continued to make such means possible. 


(1) With the introduction of sound apparatus into the theaters, 
the responsibilities of the projectionist have been greatly increased. 
The theater owner's investment also has risen proportionately. 
It is to the mutual interest of both owner and projectionist that the 
fullest measure of value be extracted from each and every item of 
equipment (consistent, of course, with the quality of the performance, 
which must always be the first consideration). 

(2) The Committee feels that a detailed account of each and 
every item of work performed by the projectionist will not be of 
much practical value as such details vary greatly with each in- 


stallation and type of performance. The Committee, however, 
desires to outline a general system of routine which will illustrate 
the close attention required for the proper functioning of equipment 
and for the perfect presentation of sound film entertainment. 

(3) A printed form should be provided for the projectionists' 
daily report. This form should include space for entering each 
film or other subject included in the performance, and blank columns 
for entering the starting time of each subject on every performance. 
It should include the names of the projectionists on duty, with the 
starting and finishing time opposite each name. Spaces for reports 
as to the condition of film, the condition of equipment, supplies 
needed, supplies received, irregularities and imperfections of per- 
formances should be provided, in addition to space for records of 
vacuum tubes put in service or removed and the number of hours 
of use at time of removal. 

(4) This form may be made in duplicate, one being retained in 
the projection room and the other being sent to the manager. 

(5) It is fully as important to retain a record of the projection 
room as it is with every other branch of the business. By keeping 
this daily record accurately, both manager and projectionist can read- 
ily determine conditions of equipment and supplies. In many cases 
they are thus able to eliminate waste. 

(6) Projectionists should report each day, sufficiently in advance 
of the scheduled opening time of the performance, to make the 
necessary horn and other tests of projection and sound equipment; 
to ascertain if batteries are in proper condition; observe meter read- 
ings; check projectors for equal volume; remove from charge such 
batteries as are intended for immediate use at least one-half hour 
prior to such use ; and observe condition of vacuum tubes. 

(7) They should consult the schedule of performances, noting 
particularly any deviation from previous schedules; consult the 
bulletin board for information or cues left by other members of the 
projection staff; clean interior of lamps, arc contacts, reflectors, 
condensers, objective lenses, and fader; and examine arc leads for 
corrosion and test connections for tightness. 

(8) They should lubricate the projectors and let them run for 
several minutes, noting whether they maintain an even speed of 
ninety feet per minute; stop projectors, clean film trap, sprockets, 
and fire rollers, and wipe excess oil from bearings to prevent accumu- 
lating oil on film; check projector mechanisms for proper tension 


of take-up and film tension pads, for proper clearances of pad 
rollers, fire valves, and film trap, and for tightness of all set screws 
of connectors. 

(9) They should then check the exciting lamps for discoloration, 
condition of filament, and proper line-up ; see that the sound optical 
system is free of oil; rewind and examine film. If new program, 
rewind and examine film prior to first showing, observe if change- 
over marks are properly placed and if any defect, such as oil ac- 
cumulations, scratches, buckling, strained or broken sprocket holes 
are apparent. Such defects should be reported immediately. 

(10) Such parts of projection and sound equipment as do not 
require daily cleaning, lubricating, or inspecting should have a 
designated day of the week assigned for receiving such attention. 

(11) The procedure as outlined above, if properly carried out, 
will guard against film damage. Faulty adjustments or worn parts 
will cause film damage a cause of great loss to the industry. Film 
in bad condition, faulty adjustments, or worn mechanisms create 
possibilities of film fire, with its attendant danger and financial loss. 

(12) In projecting picture or effect, the projectionist should 
strive to avoid imposing any distraction on the audience which 
would serve to destroy the illusion, such as flickering light, shaking 
or moving the projected image. 

(13) He should be constantly alert in maintaining even illumi- 
nation, sharp focus, smooth change-overs, and proper timing of 
opening and closing of curtain. He should fade the picture or effect 
on and off gradually, to convey an agreeable and smooth effect to 
the audience. 

(14) He should be stationed constantly at the projector while 
it is in operation, and should be promptly responsive to signals for 
adjustment of volume. 

(15) Where the control of the curtain is not directly handled 
from the projection room, a pre-arranged system of warning and 
closing signals should be used. Such signals usually consist of a 
two-buzz warning to the stage which is acknowledged on a return 
buzzer. A one-buzz signal is given at the moment of opening or 
closing of curtains or changing screen masking for various-sized 

(16) Film should be examined after each run and checked for 
loose splices and scratches, and if oil has accumulated on the film, 
it should be wiped off and the projectors checked immediately to 


eliminate further scratching. Projectors also should be wiped dry 
of oil after each reel and checked for accumulations of emulsion from 
the film. 

(17) Where more than one projectionist is on duty and when a 
projector has been threaded, the arc trimmed and fully prepared 
for the showing of each succeeding reel, the projectionist completing 
this work should step to the running projector and relieve the other 
projectionist, to allow him to check each detail of threading and 
trimming, noting that the proper reel has been placed in the pro- 
jector. This routine of checking should be firmly established in the 
projection room as it has been the means of discovering faulty 
threading and incorrect reels in time to make corrections and avoid 
interruptions or film damage without making such errors evident to 
the audience. 

(18) A minimum supply of spare parts should be determined 
upon. An accurate record of necessary spare parts and supplies 
should be kept by projectionists, and when items are used which 
reduce the amount below the minimum figure, such items should be 
reported in the "Supplies Needed" column of the projectionists' 
daily report. 

(19) When ordering parts, the correct technical designation and 
catalog number should be given wherever possible in order to avoid 
error in delivery. Catalogs of main items of equipment should be 
filed in the projection room for reference. Parts subject to breakage, 
such as gears, vacuum tubes, and connectors, should be distinguished 
from parts which are subject to gradual wear, and additional pre- 
cautions should be taken to provide against emergencies arising 
through such breakage. 

(20) To provide against accidental breakage of spare vacuum 
tubes, they should be stored in their individual boxes. Tubes, as 
well as other spare parts, should be further protected by being 
placed in a large metal cabinet containing shelves and equipped 
with a lock and key. This manner of storing will facilitate a rapid 
inventory checking of spare parts. 

(21) Proper attention should be given by the projectionists to 
the matter of maintaining the proper level of electrolyte in batteries. 
The avoidance of over-charging or over-discharging will result in a 
full useful life of the storage batteries and, conversely, a lack of such 
attention will result in a very greatly shortened life and consequent 
waste and expense for replacement. 


(22) Where a generator is used in place of batteries it will be 
necessary to inspect the commutator each day and wipe it off with 
cheesecloth moistened slightly with vaseline. If this practice is 
regularly followed, the commutator should remain in condition for 
perfect sound reproduction. 

(23) Exhibitors should acknowledge the good work of the pro- 
jectionists in maintaining the equipment in the best condition and 
should be willing to institute new ideas and install new appliances 
which contribute to better performance or increased efficiency. 

In conclusion, it is the belief of the Committee that every owner, 
manager, and projectionist should take cognizance of the fact that 
the projectionist is in a position to contribute measurably to the 
advancement of the industry. Every projectionist should manifest 
a desire to conduct his work so that optimum screen results are 
efficiently secured. 

Systematizing the routine work in the projection room is highly 
important, for it is only by the orderly arrangement of the many 
complex details that: 

(1) thorough inspection, servicing, and checking of equipment 

can be made ; 

(2) equitable working arrangements, discipline, and harmonious 

cooperation between projectionists can be had; 

(3) efficient results from projection and sound apparatus ob- 

tained ; 

(4) smoothly conducted performances secured. 

HARRY RUBIN, Chairman 





J. H. GOLDBERG, Chairman H. GRIFFIN, Chairman 







H. B. SANTEE, Chairman J. J. HOPKINS, Chairman 









P. A. McGuiRE 


MR. LINTON: I take this opportunity to extend my thanks to the Committee 
for the completeness and magnitude of the report. Projection practice varies in 
different types of theaters and with the kind of program put on. We have little 
control over this, and, for that reason, I am sure that this report will be of great 
interest to all projectionists. 

PRESIDENT CRABTREE: What is the objection to wearing one earphone for 
judging the volume? 

MR. GRIFFIN: There are so many extraneous noises that it is impossible to 
obtain satisfactory results with an earphone. 

MR. C. GREENE: Several years ago I had the opportunity of examining the 
Mechau projectors which were at the Capitol Theater and when spinning them 
by hand I was particularly struck with the ease with which they turned and 
with the silence of their operation. A non-intermittent projector that would 
run as silently as that one did would be a great boon to a sound projection room. 
A pneumatic rubber earphone, sold for years by office supply houses, originally 
designed for the Bell Telephone receiver, will fit the majority of standard double 
head sets. It fits snugly at the side of the head around the ear and leaves the 
entire ear free and normal not under pressure and seals out a surprisingly 
large amount of extraneous noise. 

MP. GRIFFIN: The occasional use of earphones involves no difficulty, but I 
do not believe any projectionist would like to wear them throughout the entire 
day. A type of headset which would exclude extraneous noise would also make 
it impossible for the projectionists to communicate with each other. The Com- 
mittee feels that the desirability of using headphones is very doubtful. 

MR. GREENE (communicated): Naturally, I do not expect headphones to 
be used continuously. However, I wear my cushioned set at the opening of each 
performance and entirely through each rehearsal with no discomfort. 

PRESIDENT CRABTREE: Cannot a horn or baffle be placed close to the projec- 
tionist as he stands at his machine? By placing his ear close to the horn he may 
be able to obtain a measure of the volume. 

MR. SANTEE: The main difficulty with the headset is the nuisance of the 


cord attached to it and the danger of its becoming entangled in the moving ma- 
chinery. There is already a horn connected to the output of the amplifier, which 
does not give the volume obtained in the auditorium but a measure of the volume 
coming from the system itself. I assume you refer to a horn connected to a micro- 
phone in the auditorium. It is very difficult to calibrate a system of that kind, 
as pointed out in the report. A variable quantity, in the form of an amplifier, 
is between the microphone and the loud speaker. The substitution of a tube of 
different characteristics would destroy a calibration and make it impossible to 
judge correctly the volume in the auditorium. 

MR. HARCUS: It is the object of the studios to send out pictures which will 
not require cueing during the running of the show. This is being accomplished 
quite successfully by most producers, desired changes of volume being recorded 
into the sound track so that with uniform house conditions the show will run on 
one fader step. If the two projection machines are balanced for volume and 
quality, and the manager calls for changes of volume as the house fills and empties, 
ordinarily all the essential showmanship will be properly cared for. There are a 
few exceptions to this at the present time, such as in musical shows where songs 
should be played up a step or two above "normal," and in pictures where the effect 
of some spectacular scene is enhanced by momentarily raising the volume several 

MR. SANTEE: That is covered in the Report of the Sound Committee. 


The Sound Committee, in preparing this report, has confined 
itself mainly to a consideration of the status of present-day practices 
in sound recording and reproducing. Some study has also been 
given to the possibilities of standardization as well as to those items 
which might well be investigated further. 

Where a practice has proved itself worthy of usage it is the plan 
of the Committee to recommend it for standardization to the Stand- 
ards Committee of the Society. It is recognized that in an art so 
comparatively young as sound recording and reproducing, care 
must be taken against premature attempts at standardization. 
The progress of development is so rapid and the technic of 
recording and reproduction is undergoing adjustment so quickly 
that premature attempts at standardization might prove a hindrance 
rather than a help. On the other hand, the moment any phase 
of the art becomes stabilized, it should be presented at once as a 
matter worthy of standardization throughout the industry. 

In this report the Committee intends to show a cross-sectional 
view of the newer and more important phases of sound recording 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 


and reproducing. It is not intended that the material presented 
here shall encroach upon the activities of the Progress Committee 
although there may unavoidably be some slight duplication. 

Neither the Committee nor the Society now has facilities to carry 
on investigations, but it can recommend what is of importance for 
further progress in the art. The Committee, therefore, feels it 
may be of considerable service in presenting to the Society and to 
the industry matters on which work should be done. Some of the 
items which have been suggested to the Committee as worthy of 
consideration have already received sufficient study to permit the 
formation of definite recommendations. In these cases, arguments 
for and against are presented and the Committee's conclusions sub- 

Part I 


Directional Sound Detectors. A directional sound detector com- 
prises a device in which the efficiency of response is a function of 
the angle between the direction of incident sound and a reference 
axis in the system which coincides with the direction from which it 
is desired to receive the sound. 

In general, there are two principles used in directional sound de- 
tectors, one amplifies the sounds desired by concentrating them 
and the other avoids or suppresses the unwanted sounds. Horn 
and reflector types employ both principles. The ribbon microphone 
and absorptive baffle make use of only the second. 

Horns. Horns have been long used in conjunction with various 
types of sound reception apparatus, but have not been used for 
high-quality pick-up due to the difficulty of obtaining a good fre- 
quency characteristic in spite of the apparent efficiency of this type 
of unit. 

Reflectors. The use of reflectors for the reception and focusing 
of sound is well known. In order to receive sound pressure varia- 
tions over a wide frequency range, it is necessary to use a reflector 
having large dimensions. Within practical limits of size, a reflec- 
tor is likely to have a characteristic which will be better at the high 
end of the frequency scale than at the low end, although compensa- 
tion for this effect can be applied. 

Combination of Horn and Reflector. It is possible to combine the 
horn and reflector principles in a device which has a fairly good re- 
sultant frequency response. The directional properties, however, 


as limited by the design of a horn and a reflector, may not be uni- 
form with frequency. 

The directional characteristics of these devices have been found 
useful in eliminating undesired sounds and noises, particularly where 
the sound which it is desired to pick up is weak. The effectiveness 
has been greater for outdoor work where there is no reflected sound 
than for use in studios where reverberation is encountered. 

Ribbon Microphone. A properly designed ribbon microphone may 
be made very directional. Its directional characteristic is practi- 
cally independent of frequency because of its dimensions, and, by 
virtue of its directional effect, increases the distance from which 
acceptable sound may be picked up, in spite of the fact that it re- 
ceives a relatively small amount of energy due to its size. It is also 
particularly effective in reducing unwanted sounds, such as camera 
noises and the like. 

Absorptive Baffle. It has been found possible to design an ab- 
sorptive baffle for a microphone in such a way that any sound coming 
from a direction not included in the throat angle of this absorptive 
structure will reach the diaphragm at a very much reduced intensity. 
This structure, while fairly large in dimensions in order to obtain 
the necessary absorption, is not dependent entirely upon the wave- 
length of the lowest frequency for its minimum dimension since the 
wave front remains practically undisturbed. This arrangement, 
of course, is no more efficient than the microphone would be with- 
out the absorptive device but its sharp selectivity of the direc- 
tion from which it effectively receives sound makes it appear 


Silencing of cameras became necessary with the advent of talk- 
ing pictures. While the ideal method would be to use a silent camera, 
until such perfection is attained, it is necessary to place the existing 
cameras in some form of silencing box. This, in the first place, took 
the form of a camera booth large enough to house one or more cameras 
and the cameramen. Being extremely cumbersome and heavy, it 
was in some cases very difficult to place on a set and of necessity 
soon gave way to handier methods. 

During this preliminary stage, much thought and work went 
into the methods of camera maintenance which resulted in their 
being brought to a higher state of mechanical perfection than had 


ever before been attempted in the industry. It was also found that 
the commonly used means of interconnecting the camera and the 
camera drive motor by a flexible shaft was a great source of noise. 
This camera drive was a development of talking picture equipment 
which the weight of the early motors made necessary, as it was not 
practical to hang much weight on the camera structure. 

At this period each studio investigated camera silencing in its 
own way. By a process of experimentation and elimination, the 
present-day devices were evolved. They are by no means ideal 
and are being continually changed and improved. The generally 
accepted opinion is, of course, that the ultimate solution of this 
problem will depend on the development of a silent camera which 
it will not be necessary to enclose. 

In camera booths, the natural development was along the lines 
adopted by most studios (with a few exceptions), that is, an indi- 
vidual camera enclosing box which, in its early stages, was simply 
a wooden framework covered with various sound insulating materials. 
This did not silence the camera sufficiently to permit its use within 
fifteen or twenty feet of a microphone and it was soon replaced by 
more efficient designs. It is unnecessary to follow the various 
stages of this development, but from a survey of the present-day 
equipment it is easy to see that it is simply an elaboration of this 
silencing box. 

The new camera silencing devices became known as "blimps" or 
"bungalows." In the majority of cases the bungalow was made to 
contain the drive motor as well as the camera. Some of the studios 
adopted a form of drive motor which was mounted directly on the 
camera; others retained the flexible shaft but enclosed it inside the 
bungalow. One or two of the studios made separate bungalows 
for the motor and the camera, and covered the flexible shaft with 
heavy layers of sound insulating material. 

The Fox Movietone Studios adopted as standard a camera bag 
composed of rubberized cloth, kapoc floss, and other soft insulating 
materials, fastened by means of zippers and snaps. The lens and 
finder protrude through the bag. 

With the adoption of the heavy bungalow covered camera, a very 
much stronger and more rigid camera-tripod became necessary. 
The bungalows used by Warner Brothers and United Artists are 
light enough to mount on the standard tripod. Most of the other 
studios adopted either a tripod which was developed by Metro- 


Goldwyn-Mayer in collaboration with Pathe*, or else an adaptation 
of this, used in conjunction with a standard tripod for rigidity. 

The Academy of Motion Picture Arts and Sciences, under date 
of May 14, 1930, published through their Technical Digest Service, 
Report No. 3 of the Producers-Technicians Committee relating to 
camera silencing. This report gives in detail a complete resume 
of all such devices in use at that time. It includes information on the 
insulating value in decibels, the methods of construction, materials 
used, and the distance that a microphone can be used from the camera. 


The noiseless method of recording on film, announced at the end 
of 1930, appears to be receiving general acceptance throughout the 
industry. RCA Photophone has described two methods of effecting 
noiseless recording on variable width track. One of these displaces 
the zero line on the track in such a manner that the clear portion 
is only just wide enough to carry the modulation. This is subject 
to the disadvantage that weaving in the projector may cut off some 
of the weaker sounds. The second method uses a movable shutter 
during the recording which causes the clear part of the sound track 
to become blackened in those portions which are not employed to 
carry the modulation. 

The Western Electric Company has announced a noiseless record- 
ing system which is applied to their variable density method. The 
density of the sound track is increased during the intervals in which 
the sound volume is low, and is decreased according to the envelope 
of the sound currents in such a manner that the film is always just 
able to accommodate the required modulation. 

The Fox organization has devised a means for flashing lamp 
variable density recording, in which the intensity of the lamp is 
reduced during the intervals of low sound amplitude, the intensity 
being altered during the process of recording. 

A number of independent makers of sound equipment, most of 
whom are using the flashing lamp, have announced attachments to 
their equipment which produce essentially similar effects. 

The reduction of noise is accomplished during the actual recording 
by an attachment to the recording system, and, in general, involves 
no change in recording or processing technic. The amount of noise 
reduction vihich is being employed in most studios at the present 
time is of the order of 10 db. 



Extensive investigations have been made by many interested in 
the factors concerned in set and studio acoustics and theater acoustics. 
In some cases these studies have been made with recently developed 
instruments, permitting more accurate results than those previously 
obtained by aural methods. Several factors have been discovered 
by such means, some of which have contributed to the development 
of a more general formula for the computation of the time of re- 
verberation. The application of this formula, which has been pub- 
lished by Dr. C. F. Eyring, of the Bell Telephone Laboratories, is 
of particular value in set and studio work, where average absorp- 
tion coefficients are comparatively high. Important studies of the 
effect of relative humidity on sound absorption are being made. 

The necessity for consideration of the reverberation existing 
throughout the frequency spectrum is now well appreciated. Where- 
as many enclosures had in the past been acoustically treated, giv- 
ing consideration only to the reverberation at 512 cycles, experience 
in many of these cases indicates the necessity for obtaining suitable 
balance between the reverberation at the low and high ends of the fre- 
quency spectrum relative to that in the central portions of the range. 
It is becoming the practice to adjust theaters and recording studios 
to have times of reverberation throughout the frequency spectrum 
such as will give definite rates of decay for sounds of equal loudness. 
With the application of suitable accurate instruments for the mea- 
surement of reverberation times, studies have been made of the rela- 
tive effects of connected volumes, which have an important bearing 
on complex auditoriums, as well as on recording sets on large stages. 
Further study, by instrumental means, has indicated the erf ect of 
direct reflections to be of importance and requiring consideration 
in the design of auditoriums, in addition to the consideration given 
the reverberation time. 

The importance of maintaining a very low noise level has been 
extended to cover not only the studio, but the theater. This has 
become more necessary with the development of recording methods 
insuring a lower background level in the sound picture. Attention 
must be given to the transmission of noise from the projection room 
into the theater, from the ventilating systems, from sources external 
to the auditorium, and to miscellaneous noise sources within the 

More information is available upon the acoustic power required 


to provide satisfactory sound volume in an auditorium. It is, there- 
fore, possible to predict more accurately what effect the introduction 
of absorbing material into an auditorium will have upon the sound 
volume and, where necessary, upon the electrical requirements of 
the system. 

Many improvements have been noted in existing commercial 
materials and a large number of new materials suitable for studio 
and theater use have been developed and introduced in the past 
year. This has considerably widened the field for obtaining ma- 
terials having the desired acoustic characteristics for the particular 
application and which will be more readily acceptable from the stand- 
points of architectural appearance, fire hazard, and cost. 


The Committee has been fortunate in receiving from a firm promi- 
nent in the film industry the results of tests, conducted over a period 
of two years, of processes which purport to preserve motion picture 
film. The method used in these tests was to prepare loops of film, 
half of which were processed and half unprocessed, both sections 
being taken from the same reel or roll. These loops were projected 
300 times, with examination at 100, 200, and 300 runnings, on a spe- 
cially prepared projection machine, which caused as little wear as 

The processes tested were such as lacquer, surface hardening, 
whole surface waxing, chemical impregnation, liquid edge waxing, etc. 

The noticeable effect of the processes investigated was that the 
film became seasoned more quickly, so that during the first few 
times of projection, the emulsion did not collect on the shoes and 
tracks of the projection machine as is often the case with green 

There was also indication from this set of tests that liquid edge 
waxing provides comparable protection. Once past this initial 
period, however, it was not evident that the processes provided any 
material improvement in giving greater lasting qualities to the film. 


In recent years several talking motion picture equipments have 
been developed and offered for sale for home use. Practically all 
of these equipments use a 16 mm. projector with either a flexible 
shaft or geared connection to a synchronous turntable for disk repro- 


duction of sound. All the devices examined, except one, project I 
24 pictures per second and employ a turntable driven at 33 Va rpm. 
This one exception projects 16 pictures per second and the projec- 
tor and turntable afe driven by electrically interlocked motors. 
In order to maintain synchronism with the 33Vs rpm. turntable, 
every third frame is removed in printing from the negative to the 

At the present time 16 mm. films synchronized with sound are ' 
difficult to obtain and are expensive. If an extended library of films 
were available, it is probable that a larger demand would appear 
for home talking movies. To date, the supply of films is extremely 
limited and these films are available only in the larger centers, re- 
quiring personal application to obtain them and personal return. 
This mitigates against very extended use of these films and is a serious 
detriment toward obtaining a large market for the reproducing equip- 
ment in the home. 


Considerable demand is apparent for talking motion picture equip- 
ment for non-theatrical uses, this equipment to be used either for 
advertising purposes, instruction work, in schools, churches, etc. 
Equipment for this purpose is built by all the leading talking motion 
picture apparatus manufacturers. The trend seems to be toward 
a 35 mm. film with sound on the film, although some equipment 
has been built with the' idea of using 16 mm. film and a synchronized 
disk, which permits a picture of sufficient size and brilliance of illumi- 
nation for small audiences. Libraries are being developed which 
will undoubtedly stimulate the exploitation of such equipment. 


On January 1, 1931, there were reported to be in the United States 
13,515 theaters equipped for sound reproduction and 8209 theaters 
unequipped. It might, therefore, appear that during the period 
of sound equipment installations only about 63 per cent were com- 
pleted. Many of the theaters now running silent, however, are un- 
profitable houses which may never be able to afford sound equipment. 
With the decreasing number of silent picture releases, these theaters 
may be forced to close. It follows, then, that the installation period 
is well over 63 per cent completed. Perhaps 80 per cent would not 
be too high a figure. 

It may be considered that the industry is passing out of the in- 


stallation period and is now entering a period of stability in opera- 
tion and of refinement. The novelty value of sound has passed 
with every indication that sound has become as necessary a factor 
in the theater as is the picture on the screen. 

The first problem of theater projection is obviously to keep a 
picture on the screen and to maintain sound from the horns. It 
so happens that statistics from Electrical Research Products, Inc., 
are available, which show the ratio of emergency calls to theater 
installations in the United States over a period of time. In De- 
cember, 1928, with roughly a thousand theaters equipped, the ratio 
of emergency calls per week to theaters in service was about 0.185. 
In December, 1929, with 3300 theaters equipped, the ratio had 
fallen to about 0.05. In December, 1930, when nearly 5000 theaters 
were equipped, the ratio was as low as 0.022. This decrease in 
emergency calls is caused by improvements in design and manu- 
facture, and to proper and continued maintenance of the equipment. 
It is logical to believe that the operating troubles experienced with 
other reputable systems follow somewhat the same general course. 
It is consequently obvious that the first requirement of sound pro- 
jection, namely, consistent and reliable operation, has been achieved. 
The quality of sound now focuses our attention. 

Poor theater acoustics constitutes one of the most serious causes 
of poor sound reproduction in theaters. Acoustic analyses have 
been made in a large number of theaters and corrections of the con- 
ditions have been made in some cases. It often happens that the 
theaters less able financially to make the correction need it most. 
It has been proved in so many cases that improved acoustic condi- 
tions result in increased box-office returns that the expense of the 
change has been thoroughly justified. It is believed and hoped 
that more theaters can avail themselves of this improved condi- 
tion not only for their own salvation but to give to the public all the 
benefits of the improved products which could not otherwise be 

There has probably been a healthy although unconscious compe- 
tition between the studio and the theater in striving toward higher 
quality. Such improvements as better reproducers for disk records, 
finer optical systems, and smoother mechanical features for film 
reproduction, along with other general advances applicable to both 
methods, have raised the standards of the theater equipment to the 
point where they are capable of handling good quality recordings. 


Improved technic in the studios, resulting from such factors as study 
of stage and set acoustics, microphone placement, better knowledge 
of re-recording methods, and more exact control of film processing, 
have made it possible for the studios to show a tremendous improve- 
ment in the quality of the recorded product. 

The gradual extension of the frequency range has been a material 
contribution to this improved quality but efforts toward a greater 
range should be and are being continued. 

Part II 


The considerations which dictate the preferred sound track size 
and location are twofold first, engineering, and, second, economic. 
For the present the second of these dominates. Engineering con- 
siderations tend to favor an increase in sound track width over the 
present track, although such an increase cannot be carried on in- 
definitely without encountering further engineering difficulties. 

A number of locations for the sound track differing from the 
present have been proposed. The majority of these offer little to 
be gained from an engineering standpoint. Their effect is mainly 
to permit a change in the present picture size, and the principal 
difficulty standing in the way is an economic one. Until it has 
been possible to make a further engineering study of this problem, 
it would appear to be undesirable to disturb the producers' and theater 
owners' efforts to stabilize their economic positions by the intro- 
duction of equipment necessary to effect a relatively slight engineer- 
ing or artistic improvement. 


At the time when sound recording and reproducing was just 
getting a start, the need for double film was felt rather strongly. 
Some difficulty was experienced in the proper processing of both^ 
sound and picture on the same film, and, in addition, the theater 
reproduction apparatus was less effective than it is today. At that 
time the industry was often able to obtain better than normal re- 
sults by using the double film. 

. At present the situation is quite different. Theater reproduc- 
tion apparatus has been greatly improved, and, moreover, a large 
part of the available theaters have been provided with sound ap- 


paratus at considerable cost. To supersede this apparatus or to 
modify it in any way would represent a substantial increase in cost 
to the theater and would present an economic problem which should 
not even be proposed unless substantial advantages are to be derived 
from the change. 

Separate sound film installations would permit: 

(1) control of sound film independent of the picture; 

(2) separate handling of the release print in processing; 

(3) wider sound track ; 

(4) higher running speed for sound track. 

There are no data existing to show that these improvements 
warrant an expensive change. In the first place, it is no longer 
considered a serious handicap to the sound record that in variable 
density records a negative development must be accommodated to 
the processing of the composite print. By proper choice of condi- 
tions, satisfactory results can be obtained differing only in volume 
from what might be obtained with the separate sound film. Noise 
reduction technic applied to the composite sound record is adequate 
for practical theater requirements. 

Secondly, studio and laboratory technic has found practical solu- 
tions of most of the problems of development of picture and sound 
records on the same film, in positive form. This did not always seem 
feasible, but present results indicate no particular handicap. As 
a matter of fact, the positive control enforced by sound requirements 
has produced a general improvement in average picture print quality 
in many cases. 

Somewhat the same reasoning applies to the wide sound track. 
With the track twice as wide as at present, an improvement of the 
order of three db. in signal-to-noise ratio should be obtained, with 
no change in quality. This improvement is scarcely sufficient to 
justify a large change in theater apparatus, in the light of noise re- 
duction studies which are at present under way. 

The case of high running speed for the sound track has advantages 
since the greater the speed of the track the greater the ease of re- 
cording high frequencies. There should certainly be no difficulty, 
however, in recording frequencies up to 6000 or 7000 cycles on 
existing film stock running at the present standard speed. The 
present recording and reproducing equipment, at least with modifica- 
tions and improvements which will be made as the art progresses, 
should be capable of recording and reproducing this frequency 


range. It would, therefore, seem wise to exert efforts to obtain 
good, clear reproduction with present facilities rather than to intro- 
duce additional means for extended range at this time. Ultimately 
the state of the art may warrant the recording and reproduction of 
very high frequencies in the audible range but it is not believed that 
the time is opportune to consider costly changes toward this until 
full advantage is taken of present equipment. 

An important economic phase of the handling of film is the mecha- 
nism of release through the exchanges. Handling and shipping prob- 
lems are such that the extra cost and complication of handling a 
separate medium for sound is almost prohibitive. Moreover, the 
problem of maintaining synchronism must be admitted. No num- 
bering system, however complete, can be as satisfactory in this 
respect as to have the picture and sound records unalterably tied 
together on the same film. Even at present, the producers annually 
furnish thousands of feet of short replacements to take care of in- 
advertent or deliberate changes of a print in the exchange or theater 
to accommodate a particular situation. It has never been possible, 
thus far, to prevent such changes being made. Obviously, it would 
be very much harder to handle this phase of the problem on a double 
medium basis. 

In the light of this brief analysis, it is the Committee's definite 
recommendation that the Society should take a stand in favor of 
improvements known to be possible in the present standard com- 
posite picture and sound print. 


In the recording of sound for audible pictures, the volume range 
of the sound record is defined on the upper side by the overload 
point or the sound track and the cutover point for the disk, and 
on the lower side by the masking effect of the inherent noises in the 
sound record, known as ground noise or surface noise. This vol- 
ume range was originally in the neighborhood of 30 db. and there 
was little choice between film and disk. As pointed out elsewhere 
in this report, the adoption of noiseless recording systems has in- 
creased the volume range on the film record by approximately 10 db. 

In order to obtain a satisfactory ratio between the sound and 
noise level it was the custom in the past to raise the level of the 
weaker passages and lower the level of the louder passages at the 
time the record was made and to furnish the theaters with cue sheets 


directing the projectionists to lower or raise the sound level at these 
points by amounts specified in the cue sheet. In practice, this has 
not proved entirely successful, as the projectionist's attention has 
been so largely occupied by other, matters that he has been unable 
to properly follow the instructions given in the cue sheet. It has 
been found practicable to record the sound on the film at the levels 
at which it is intended to be reproduced in the theater. The cue 
sheet is, therefore, being abandoned. Consideration is being given 
to marking on the beginning of each reel in appropriate fashion the 
relative levels at which the reels should be reproduced. 

The Committee will give further consideration to this important 
problem but suggests at this time that the trend be continued toward 
recording the sound at the proper levels. 


During the past year, radical changes have taken place in film 
developing. Almost universally, the use of machines for release 
prints has become standard practice. The developing of picture and 
sound negatives by machine has become almost general, as the re- 
sults of machine development have proved to be superior in ob- 
taining uniformity and freedom from mechanical injury. A matter 
that requires further study is the composition and maintenance of 
the chemical bath. 

Although information is available to permit the proper develop- 
ment of sound film, and devices for controlling and checking the 
methods are at hand, the full use of such facilities is not yet 
being made. A uniform and consistently good product can only 
be obtained by constantly employing such instruments as a means 
of checking the results. 



H. B. SANTEE, Chairman 


The New Copper Oxide Cell. M. ARNDT. Phot, hid., 29, Feb. 25, 1931, pp. 
237-8. The photoelectric effect or flow of electrons from a metal exposed to 
light has found application in the potassium and caesium cells, such flow being 
accelerated by including a battery in the circuit. A certain amount of energy of 
the incident light is necessary to initiate the flow of electrons. It has been found 
that a metallic salt in contact with the metal requires a relatively low level of 
energy to start the flow of electrons. This has found practical application in the 
new copper oxide photoelectric cell which is described by the author. Further 
developments of this kind would seem to be of importance to the future of sound 
films. . C. E. M. 

New Debrie Sound Film Camera. Phot. Ind., 29, Feb. 25, 1931, pp. 238-40. 
The new models seem well designed to meet all the requirements of sound film 
exposure. . The camera stand rides on three rubber tired wheels controlled by an 
ingenious steering mechanism. The stand is made entirely of metal with an 
aluminum base containing the motors, resistance, etc. At the rear is a small plat- 
form for the operator. The camera is enclosed in a sound-proof housing which is 
mounted in a yoke upon a pillar so that it can pivot in a vertical plane. 

C. E. M. 

Sound Recording Apparatus for Expeditions. H. FREESE AND H. LICHTE. 
Kinotechnik, 13, Feb. 5, 1931, pp. 44-7. The need for sound recording apparatus 
that can be transported to the field by rail, ship, porter train, etc., and still give 
results equal to those obtained with the apparatus of the studio, has caused 
Klangfilm G. m. b. H. of Germany to construct equipment that is contained in a 
number of water-proof cases. When the equipment is operating on location, power 
is generated by a two-cycle, single cylinder gasoline engine located 200 mete'rs from 
the scene of action. This drives a 220-volt direct current dynamo. A transformer 
is located 50 meters from the scene, arranged to supply 1000, 135, and 15 volts for 
the plates and filaments of the amplifier tubes, driving motors for the sound and 
picture cameras, etc. At this distance are located also the control panel, sound 
camera, and amplifier, housed in a tent. Telephones, power cables to the picture 
cameras, and cables for the microphones run thence to the scene. The apparatus 
described is intended for features or short pictures. Cheaper and simpler ap- 
paratus is used for news recording. M. W. S. 

Motion Picture Education in Japan. Y. MIZUNO. Internal. Rev. Educational 
Cinemat., 3, Jan., 1931, p. 5. The history of the movement is given. Japan pro- 
duced 718 theatrical films in one year. About 2 per cent of the films produced 
are educational. About 30 cinemas in Tokyo hold a children's movie day periodi- 
cally on Sunday. The All- Japan Association of Cine Education directs the use of 
educational films in Japan, in the schools, factories, and for the women through a 
women's society. Sub-standard film is in wide use in the schools. R. P. L. 

The Film Collection of the Austrian Ministry of Education. G. A. WITT. 


Internal. Rev. Educational Cinemat., 3, Mar., 1931, p. 213. An archive for impor- 
tant educational, cultural, and historical films has been instituted in Vienna. 
Both standard and sub-standard films are lent out and even projectors and cam- 
eras. It is also a center for information on cultural films. R. P. L. 

Cinema and Visual Fatigue. G. D. F. Internal. Rev. Educational Cinemat., 3, 
Jan. and Feb., 1931, pp. 53 and 165. Another installment of the report of the in- 
vestigation. Programs for children ought not to last longer than 10 to 15 min- 
utes without a rest period of several minutes. The cinema should be forbidden 
for children under 16 after a certain hour in the evening. Only 14.5 per cent out 
of 19,661 children complained of bodily fatigue. R. P. L. 

Empty Seat Indicators. Film Daily, 55, May 31, 1931, p. 8. A system has 
been developed which makes it possible for the management of a theater to know 
at all times the seating of the house. By its means, the exact number of seats 
available in every section may be transmitted to the lobby of foyer quickly and 
accurately, resulting in the seating of waiting patrons immediately as seats be- 
come available. The system is said to consist of a number of dial sending stations 
located in various aisles, and a receiving station in the main lobby. By operating 
the dial at the sending stations, the ushers in any aisle may signal the number and 
location of the seats available. C. H. S. 

New Continuous Projector. Film Daily, 55, May 14, 1931, p. 64. A film pro- 
jector called the "Kinisophote," operated on a continuous principle, has been in- 
vented and successfully demonstrated in Madrid, Spain. The machine runs con- 
tinuously at a constant speed and the screen receives a constant amount of light, 
thus doing away with flicker. This projector permits the use of very thin (cello- 
phane) film, which is driven by a single claw as only one side of the film is perforated. 
The sound track is placed in a 5-mm. space along one side, so that the section 
for pictures retains its normal one inch width. The film is driven at a constant 
speed, so that the sound can be recorded at any point. Instead of the usual 
distance of 75 perforations from the corresponding frame, the sound can be placed 
immediately opposite each frame, thus avoiding the difficulties arising from cuts 
and repairs. After being wound up as used during projection, the film is not 
rewound but is picked out from the inside of the reel to be projected again. This 
operation is done by conical rollers. C. H. S. 

Industry Earns 95 Millions in 1930. Mot. Pict. Herald, 103, Sect. 1, May 9, 
1931, p. 11. Gross earnings reported by 12 companies were $421,927,400 for 
1930 compared with a total for 9 companies in 1927 of $168,060,696. Net income 
for 16 companies amounted to $94,833,067 in 1930 compared with $45,218,670 in 
1927 for 12 companies. Gross earnings are not included for Paramount, Univer- 
sal, Eastman Kodak Company, and National Screen. G. E. M. 

Sound-on-Film for Home Movies. A. J. KOENIG. Electronics, May, 1931, p. 
621. A discussion of the problems involved in the recording of sound on 16 mm. 
film. A. C. H. 

A Dynatron Vacuum Voltmeter. RINALDO DE COLA. Electronics, May, 1931, 
p. 623. This paper is concerned with the use of the pliodynatron as a means of 
obtaining considerably greater sensitivity than is possible with single-tube volt- 
meters. A. C. H. 

Acoustic Treatment for Sound-Picture Theaters. VESPER A. SCHLENKER. 

1>M2 ABSTRACTS [J. S. U. P. E. 

Electronics, May, 1931, p. 625. A general discussion of the treatment of acous- 
tics in motion picture theaters which cannot be usefully abstracted. 

A. C. H. 

The Unit of Photographic Intensity. The Present Status of Its Standardization. 
LOYD A. JONES. /. Opt. Soc. of America, June 1931, p. 361. The International 
Congress of Photography undertook several years ago to bring about a standardi- 
zation of the source of light to be used in photographic sensitometry, the interests 
of this country being represented by a committee of the Optical Society of America. 
This paper is concerned with the present status of the project and contains recom- 
mendations for a unit of photographic intensity which, however, have not yet 
been ratified by the national committees represented at the Congress. A new 
report dealing with certain features of the recommended light source will be pre- 
sented at the 8th International Congress to be held in Dresden during August, 
1931. A. C. H. 

Patent Review on Receiver Circuits and Tubes. JOHN J. ROGAN. Elec- 
tronics, June, 1931, p. 672. A brief review of the present patent situation with 
respect to vacuum tubes and receiving circuits. The important patents with 
serial numbers and expiration dates are given. A. C. H. 

Glow Lamp Sound-on-Film Recording. VERNE T. BRAMAN. Electronics, 
June, 1931, p. 679. A description of the glow lamp method of sound-on-film 
recording with special reference to the proper design of the glow lamp. The 
author has devised a special type of three electrode glow lamp, the function of the 
third electrode being to make the ignition voltage equal to the extinguishing 
voltage by allowing a very small modulated ionizing current to flow at all times. 
This ionizing current is independent of the modulated current between the normal 
electrodes, and causes the gas to remain ionized with a faint cathode glow even 
when the normal lamp current is reduced to zero. A. C. H. 

Automatic Time Delay Relay. C. HUFF. Proc. I. R. E., 19, June, 1931, p. 1019. 
In certain hot cathode, mercury rectifier tubes, no plate voltage should be applied 
for at least thirty seconds after the filament current is turned on. By means of an 
automatic time delay relay, made up of a system of relays and a telechron clock 
motor, this thirty-second delay is automatically taken care of. To prevent 
breaking the high potential plate circuit, separate transformers are used for plate 
and filament potentials. The relay closes the primary circuit of the plate trans- 
former. A complete description of the relay is given, aided by a schematic 
diagram. A. H. H. 

A Non-intermittent Camera. WILLIAM STULL. Amer. Cinematographer, 12, 
June, 1931, p. 12. The Moreno-Snyder camera, now made in Hollywood, uses an 
optical intermittent system consisting of eight rectangular piano concave lenses 
which supplement the regular lens of the camera and move with the film to correct 
its continuous motion. The effect is a steady motionless image upon each frame. 
The lens wheels are clamped and cemented so they cannot get out of alignment, it 
is claimed. A variable slit at the aperture takes the place of shutter control for 
variation of exposure and the large maximum aperture of 360 degrees makes pos- 
sible a tremendous range not available in ordinary apparatus. 

The camera includes a finder system operating through a prism, placed in front 
of the aperture by a manual control, and automatically thrown clear whenever the 
camera is started; also a novel photo-cell exposure meter which actuates a dial at 

Aug., 1931] ABSTRACTS 283 

the rear of the casing to indicate correct exposure for the particular lens and slit 
adjustment used. An artificial frame line is put in the film by a masking device 
in the matte box which must be set after focusing and adjusting the lens aperture. 
The new camera is stated to be noiseless and capable of operating at any speed 
between eight and three hundred frames per second. A. A. C. 

1930 Equipment Exports Gain. N. D. GOLDEN. International Photographer, 
3, April, 1931, p. 13. Preliminary figures of the Bureau of Foreign and Domestic 
Commerce show that exports of American motion picture equipment increased 
$4,000,000 over the 1929 estimate, or approximately 80 per cent. Europe is our 
best customer, the Far East second, and Latin America third. Sound apparatus, 
which is this year reported separately for the first time, accounts for four-fifths of 
the total volume of export business. A. A. C. 

Stewart- Warner 16 Mm. Camera. International Photographer, 3, April, 1931, 
p. 25. A manufacturer's announcement states: "The camera is compact and 
light, 2 by 5 by 8 3 / 4 inches, is made of duralumin throughout, with an etched 
satin-finished case ; weighs 3 Y 2 pounds when loaded with 100 feet of film, and 
will retail at $50.00, with carrying case." Experimental work on the camera was 
done in Hollywood and the plant was moved to Chicago in February. A. A. C. 

The Spicer-Dufay Process of Color Cinematography. Brit. J. Phot., 78, June 
5, 1931, p. 22 (Color Suppl.). This color process uses a mosaic filter film me- 
chanically prepared. Dyes are applied in squares to the number of 350 per inch 
by means of an ink-resisting printing process on the film base. The emulsion, 
coated on top of a protective coating over this color mosaic, is specially made for 
the purpose, and consists of grains of relatively large size and great sensitiveness 
together with a finer material. The original negative image is obtained chiefly on 
the large grains leaving the fine grained part for development of the reversed 
positive. A projection printing method has been worked out for the making of 
prints which is claimed to be highly successful. The Spicer Company expects to 
extend this method to the production of prints on a white base material, to lead 
to a cheap and easy process of color photography for general use. A. A. C. 


Carrigan, J. B. MacFarlane, J. W. 

Cook, A. A. MacNair, W. A. 

Crabtree, J. I. Matthews, G. E. 

Haak, A. H. McNicol, D. 

Hardy, A. C. Meulendyke, C. E. 

Herriot, W. Muehler, L. E. 

Irby, F. S. Parker, H. 

Ives, C. E. Sandvick, O. 

Kurlander, J. H. Schwingel, C. H. 

Loveland, R. P. Seymour, M. W. 
Wyerts, W. 


1,805,511. Apparatus for Making Animated Pictures. A. W. CARPENTER. 
Assigned to Audio-Cinema, Inc. May 19, 1931. An animated picture photo- 
graphing apparatus having a work table on which a picture sheet is spread flat 
adjacent a compressible pad. A rigid support is provided for the pad. The 
picture is pressed down upon the pad and flattened thereagainst by means of a 
glass plate. The picture is supported by means of end clamp devices which per- 
mit the picture to be shifted away from the pad with the plate when the plate is 
raised preparatory to a subsequent animated picture operation. Successive 
pictures are produced and then photographically reproduced upon a film in proper 
sequence so that when the film is projected the object will appear to move on the 
projection screen. 

1,805,579. Portable Motion Picture Film Carrier. L. GOLDHAMMER. As- 
signed to Agfa Ansco Corp. May 19, 1931. A portable film carrier which con- 
tains a film transporting drum including a swinging holder containing pressure 
rollers for pressing the film toward the film transporting drum. A locking de- 
vice is provided for maintaining the film in position on the film transporting 
drum wherein release means may be actuated when removing the film from the 
film transporting drum. 

1,804,685. Continuous Sound Picture Projection. W. K. GRIMM. May 12, 
1931. Motion picture film is driven continuously in relation to a light reflecting 
mirror disposed in alignment with a lens system. A framing mask is arranged 
to overly the film and may be adjusted with respect to the reflecting mirror to alter 
the position of the framing mask with respect to the mirror. In as much as the 
film is moved continuously in the projector of this invention for the projection of 
pictures, the reproduction of sound from the film may be obtained from the same 
point in the longitudinal length of the film and not displaced in position along 
the film as heretofore has been necessary. 

1,805,948. Printing Machine for Sound and Picture Records. G. LANE. 
Assigned to Audio-Cinema, Inc. May 19, 1931. A machine which may be used 
for printing both the sound and picture records on a film. The printer includes 
an aperture ring having thereon a plurality of apertures of different widths and 
extents, so arranged in relation to the printing aperture, that one of the ring 
apertures may be made to occupy the desired position for printing either the sound 
or picture records, as desired. Motion pictures are printed through one aperture 
while the sound is printed through another aperture in a position displaced longi- 
tudinally of the film and adjacent one edge of the film out of line with the picture . 

1,805,594. System for Combined Television and Communication. R. D. 
PARKER. Assigned to American Telephone and Telegraph Co. May 19, 1931. 
Two people while being televised may converse with each other by telephone in- 
struments which do not interfere with the production of a full-face image of each 
party in the line of vision of the other and so placed as to produce the illusion of a 
face-to-face conversation. The telephone instruments are outside the field of 


view of the scanning apparatus in the booth which the persons occupy for trans- 
mission and reception of the television image. Each booth is equipped with 
an image integrator and analyzer and a telephone transmitter and loud speaker 
shielded from view of the television devices. 

1,806,122. Motion Picture Film Reenforced by Metal Strips. A. H. SMITH. 
May 19, 1931. The edges of the film at the perforations are reenforced by metal 
strips secured through the perforations by means of tongues which are punched 
from the strip in forming the desired perforations therein, the said tongues being 
bent around the transverse edges of the film perforations to secure the reenforcing 
strip to the film. The securing tongues are so arranged that the ends of the for- 
wardly extending tongues extend beneath the ends of the rearwardly extending 
tongues, thus forming a positive protection for the film. 

1,806,190. Method of Obtaining Stereoscopic Impressions of Motion Picture 
Images. N. ARFTSEN. May 19, 1931. Stereoscopic pictures are produced by 
utilizing light of different wave-lengths for each eye of the observer so as to bring 
the eyes into different states of adaptation, forming right and left images with 
sufficient rapidity to produce persistence of vision. A beam of light neutralizing 
the image which the eye should see is directed into each eye alternately. The 
projection system avoids the necessity of observing a picture through some form 
of rotary shutter device placed in front of the observer's eyes. Motion picture 
film having pictures arranged side by side is employed in the stereoscopic system. 
The system is based on the fact that the ability of one eye of perceiving or seeing 
a certain view remains unaffected by a light impression created in the other eye 
providing that such light impression is entirely uniform and homogeneous. A 
sudden light such as a flash or a short projection of a picture will be perceived by 
the human eye only after a certain interval has elapsed. The length of this inter- 
val, i. e., the interval between the actual emission of light rays and their percep- 
tion by the human eye and brain, is referred to as "perception time." The same 
depends to a large extent on the intensity of the light projection. The stronger 
the light, the shorter will be the perception time. One and the same light projec- 
tion appears in a lesser degree of brightness, if the eye receives an additional 
light. This additional light may be thrown into the eye from the side or from 
some other place surrounding the light projection. The stronger such additional 
light is, the longer will be the perception time of the light projection. Under the 
condition that the additional light appears in a certain (red) color, only the per- 
ception time of the same (red) colored light will be prolongated and the perception 
time of the contrasting (green) light will be of a shorter endurance. 

1,806,375. Photographic Recording by Radioactive Means. JOHN A. TIEDE- 
MAN. Assigned to General Electric Co. May 19, 1931. Figures or characters 
to be recorded on film are preferably cut into a recording drum or other surface 
which may be brought into contact or close proximity to the film and the de- 
pressions caused by the cut-in figures are then filled with a radium salt or other 
suitable radioactive substance. Then when the unexposed film is brought into 
contact with the drum those portions of the film opposite the figures are exposed 
to the action of the radioactive substance so that when the film is developed these 
figures are clearly indicated thereon. A permanent record from which film may 
be printed is provided on the engraved surface of the drum wherein the depressions 
are filled with the radioactive salt. 

286 PATENT ABSTRACTS [j. s. M. p. E. 

1,806,452. Method of Producing a Background for Motion Pictures. F. 
GULGORA. May 19, 1931. A motion picture is reproduced with a background 
produced by projecting with an ordinary motion picture machine a given picture 
substantially centrally of the screen, using a dissolving lantern slide projector at 
the same time for projecting different still pictures on said screen around the mo- 
tion picture without overlapping it, and simultaneously using a second dissolving 
lantern for projecting a still picture around the second picture projected whereby 
the picture on the screen will consist of a motion picture and two still pictures. 
Two or more motion pictures may be used together, or a single motion picture 
with one or more projecting lanterns, may be used at the same time, and caused to 
present independent pictures to be projected on a screen at different points in 
such a way as to produce a single effect. 

1,806,617. Synchronized Photographic and Disk Recording and Reproducing 
Mechanism. C. W. EBELING. May 26, 1931. Duplicate motors are provided 
for driving separate disk records for a talking picture system. The driving motors 
for each disk record are interconnected through differential gearing to the motion 
picture projector. Governing means are provided for each record table driven 
by the separate motors for maintaining the record tables in synchronism with the 
operation of the projector. The system is also applicable to a camera and disk 
record recording system for sound pictures. 

1,806,638. Scanning Disk for Television System. PIERRE MERTZ. As- 
signed to American Telephone and Telegraph Co. May 26, 1931. Scanning disk 
for television systems which is provided with apertures aligned in different con- 
centrical circles in overlapping relationship. The entire area of a field of view is 
repeatedly scanned and then each scanning line of the entire path of one complete 
scanning operation partially overlapped with two scanning lines of a preceding 
scanning operation for securing detail in the scanning operations. 

1.806.744. Silent Drive Mechanism for Talking Motion Picture Machines. 
LEE DE FOREST. Assigned to General Talking Pictures Corp. May 26, 1931. 
Separate and independent drives are provided for the picture recording or pro- 
jection and sound recording or reproduction processes in the camera or projection 
machine. The film feeding sprockets are driven as usual while the phonofilm at- 
tachment is independently driven for reducing machine noises to a minimum at 
the sound slit to avoid interference with the recording of sound. 

1.806.745. Sound Producing Device Using Modulated Flow of Gas. Assigned 
to General Talking Pictures Corp. LEE DE FOREST. May 26, 1931. A screen is 
employed as one of the electrodes in a sound reproducing system. A gas is modu- 
lated in accordance with voice currents and the flow thereof with respect to the 
screen electrode modified for the reproduction of sound. An electric tension is 
established between the screen-like electrode and an adjacent electrode for the 
reproduction of sound in accordance with the modulated flow of gas. 

1.806.746. Luminous Discharge Tube for Recording and Reproducing Sound. 
LEE DE FOREST. Assigned to de Forest Phonofilm Corp. May 26, 1931. The 
cathode in a luminous discharge tube is shaped to have a uniform thickness but 
a width which varies along its central axis so that a varied voltage across the elec- 
trodes will produce a varying negative glow which is exaggerated. The chief ad- 
vantage of this kind of glow discharge tube is to emphasize the higher harmonics 
of the recorded sound which are normally of relatively low intrnsitk-s, and are as 

Aug., 1931] PATENT ABSTRACTS 287 

a consequence inadequately recorded and inadequately reproduced by the repro- 
ducing system, particularly the loud speaker elements thereof. 

1,807,270. Visionograph Record and Method of Making the Same. CHARLES 
ALBERTI. May 26, 1931 . Two record tables are geared to operate synchronously 
with a television scanning disk. The magnetic engraving devices associated with 
each disk record are so associated with the visual recording circuit and sound re- 
cording circuit that synchronous sound and picture records may be made. One 
engraving tool is connected in series with the light-sensitive device which is con- 
trolled by the operation of the scanning disk for making a record of the visual 
signaling energy. The other record table carries a disk which is engraved by a 
device under control of the sound pick-up circuit. The gearing system insures 
synchronous operation of the recording and scanning systems. 

1,807,327. Repeating Stereopticon. J. F. STUBNER. May 26, 1931. Auto- 
matic projecting machine for Stereopticon slides wherein there is provided a 
magazine for a plurality of slides above the beam of light. The foremost slide is 
moved vertically into the path of the beam and the next foremost slide is moved 
into the path of the beam so that its lower edge strikes against the top edge of the 
first slide to eject the first slide. The ejected slide is automatically moved into 
an upright position and restored to the rear of the magazine of the Stereopticon 
for the repeat projection process. 

1.807.464. Scanning System for Television. JOHN L. BAIRD. Assigned to Tele- 
vision, Limited, London. May 26, 1931. A scanning system for television which 
includes an exploring device which provides a series of laterally displaced images 
whereof the maximum displacement is a fraction of the width of the picture, a 
plurality of light-sensitive cells (or light-sources) spaced apart across the picture 
and each appropriated to one zone the width of which is equal to the said maximum 
displacement, and means for exposing the light-sensitive cells (or light-sources) 
successively during successive cycles of operation of the exploring device. The 
scanning means has a maximum displacement sufficient to cover an area which is 
a portion only of a given field of vision with respect to any one electrooptical 
element. The electrooptical elements are so disposed that each is appropriated 
to a different portion of the field of vision by the scanning means. The electro- 
optical elements are rendered operative, one at a given time, so that elements of 
the picture are exposed to scanning action successively. 

1.807.465. Scanning System for Television. JOHN L. BAIRD. Assigned to Tele- 
vision, Limited, London. May 26, 1931. A scanning device for use in television 
where a rotating screen is interposed between a light source and an object to be 
scanned, the screen having a plurality of series of spirally arranged apertures. 
The apertures in the different series are spaced radially of the screen so that light 
rays will be passed from the light source across different sections of the object 
simultaneously. There are a plurality of light-sensitive devices each positioned 
to receive light from one of said sections of the object only. 

1,807,602. Circuit for Recording and Reproducing Sound from Film. AR- 
tor Talking Machine Company. June 2, 1931. A circuit for the reproduction 
and the recording of sound where two thermionic valves are arranged in oppo- 
sition and having a common output circuit. A light-sensitive device is con- 


nected across the input of each valve. One of the valves is subjected to variable 
light under modulation control by a film. 

1,807,737. Home Projector for Films of Different Sizes. L. GOLDHAMMER. 
Assigned to Agfa Ansco Corporation. June 2, 1931. A home type motion 
picture projector having an attachment for adapting the machine to films of dif- 
ferent sizes. A plate carrying a film guide and film sprockets is bodily removable 
from the projector and interchangeable with another plate. The different size 
sprockets and film guide are mounted on the interchangeable plates to accommo- 
date the machine to different size films. 

1,807,805. Preparation of Colored Reproductions by Imbibition. BERTHA 
SUGDEN TUTTLE. Assigned to Technicolor Motion Picture Corporation. June 
2, 1931. A method of imbibition printing for gelatin films which comprises 
wetting a suitable printing matrix bearing the image to be reproduced in the 
several degrees of development corresponding to the several contrasts presented 
therein, with a solution containing a dye having a marked penetrability of the 
gelatin film to be printed and a second dye having relatively low penetrability or 
dispersion with respect to said film and contacting the thus wet matrix with the 
gelatin film. 

Multicolor films are produced using a transparent film to which there is applied 
a coating of a solution containing gelatin, a hardening agent such as potassium di- 
chromate, and usually an organic acid such as acetic acid. The coating thus 
formed is then allowed to dry rapidly and is subsequently hardened to the de- 
sired degree. A plurality of matrix films, each bearing an image to correspond to 
one (or more) of the primary colors or to each of two (or more) complemental colors 
appearing in the reproduction to be made, is next prepared, as by suitably exposing 
and developing or light printing and developing a photographic film therefor. For 
example, where the complementary colors, red and green, are to be provided, a film 
matrix may be prepared and developed to correspond to the red portion of the 
images in the subject to be reproduced and a second matrix film may be developed 
to correspond to the green portions thereof. 

1,808,046. Film of Magnetizable Material for Episcopic Projection. H. 
KUCHENMEISTER. June 2, 1931. A film of magnetizable material having a 
magnetic sound record recorded thereon. The film consists of a metal band of 
magnetic material having a magnetic record recorded directly thereon. The band 
may also carry pictures on the surface thereof for episcopic projection. The mag- 
netic record may operate over the entire surface of the band coordinate with the 
record carrying the pictures for episcopic projection. 

1.808.077. Sound Picture Screen. W. J. SCHOONMAKER. June 2, 1931. A 
sound picture screen comprising a woven cloth formed with interstices for the 
passage of sound through the screen, where the surface of the cloth is ridged to 
provide for the evenly diffused reflection of the picture displayed. 

1.808.078. Non-inflammable Sound Picture Screen. W. J. SCHOONMAKER. 
June 2, 1931. A sound picture screen comprising a woven fabric formed with 
interstices in the weaving among the threads. The fabric is treated with a water- 
proof solution. There is a plastic non-inflammable and water-proof chemical 
compound applied to both sides of the treated fabric. The plastic compound 
covers the thread of the fabric and acts as a seal to prevent deterioration of the 
ingredients of the fire-proof solution from exposure to air and making the screen 

Aug., 1931] PATENT ABSTRACTS 289 

non-inflammable, water-proof, and washable. The plastic compound is suffi- 
ciently thin so that it does not clog up or entirely close the interstices so that sound 
from a loud speaker behind the screen readily passes through the interstices. 

1,808,137. Electrooptical System for Television. RALPH V. HARTLEY. As- 
signed to Bell Telephone Laboratories, Incorporated. June 2, 1931. A television 
system employing a separate line or channel for each elemental area of the field 
of view. The energy controlled by each elemental area of the field of view at the 
transmitter is given a distinctive characteristic, preferably a frequency character- 
istic such that the currents for all or many of the elemental areas may be superim- 
posed in a single physical circuit or medium and separated again at the receiver, 
and each elemental area at the transmitter acts continuously in its control of 
its channel so that maximum illumination at the receiver is obtained. Separate 
piezoelectric crystals of different frequency characteristics are arranged to resonate 
simultaneously for controlling light in a television analyzer. 

1,808,252. Film Gate. FREEMAN H. OWENS. June 2, 1931. The film is 
maintained in sliding contact with the light aperture by means of a spring pressed 
shell adjacent the film gate, the shell being movable with respect to the light aper- 
ture. A locking device is provided for maintaining the shell in a predetermined 
position with respect to the light aperture. 

1,808,497. Adjustable Support for Motion Picture Projection Machines. A. 
DINA. Assigned to International Projector Corp. June 2, 193 1 . The projecting 
machine is mounted for adjustment in an angular direction in a vertical plane for 
aligning the projector with the screen in the theater. The patentee points out 
that motion picture projectors are commonly mounted at the top and rear of a 
theater and must be adjusted so as to project the picture downwardly upon the 
screen. The patentee provides an angularly disposed arm which may be adjusted 
both telescopically and by an expansible and contractible screw joint for obtain- 
ing the desired angular disposition of the motion picture projector. 

1,808,864. Cinema Projection Screen. JULES E. PALLEMAERTS. May 26, 
1931. A fabric base is provided for the screen with a transparent adhesive coat- 
ing on the front of the fabric screen. A plurality of glass pyramids are placed on 
the adhesive coating with their apexes projecting from the base, and a second coat- 
ing of the transparent adhesive flowed over the front surface of the screen so as 
completely to embed the pyramids therein. The purpose of the screen is to ob- 
tain brilliant illumination by reason of the minute reflected rays of light between 
the sides of the pyramids. 

1,897,940. Tone Quality Control Apparatus. J. E. STAFFORD. June 2, 1931. 
The sound pick-up circuit leading to the audio frequency amplifier in a sound re- 
producing system is governed by an adjustable impedance circuit which controls 
the tone quality of the reproduced sound. The modulating circuit which may be 
controlled by the phonograph pick-up or a microphone circuit connects to the in- 
put of the audio frequency amplifier system. The tone control comprises a re- 
sistance connected directly across the modulated current generating source and 
an adjustable filter circuit connected between a point intermediate the ends of 
the resistance and the amplifier. 

(Abstracts compiled by John B. Brady, Patent Attorney, Washington, D. C.) 


Recording Sound for Motion Pictures. Academy of Motion Picture Arts and 
Sciences. -McGraw-Hill Book Co., New York, N. Y., 1931, 404 pp. Price $5.00. 

A symposium of articles by leading authorities in the various phases of the 
art of recording and reproducing sound motion pictures. This book brings 
together under one cover for the first time a complete picture of the sound motion 
picture field, interesting not only to the sound engineer, but to the whole motion 
picture organization. 

Arranged under five general heads, practically every phase of the art of sound 
recording is covered, from the source of the sound motion picture of today to 
the organization of the personnel of a sound recording organization. 

Sound recording on disk and film, both the variable area and the variable 
density methods, is covered by articles explaining the theory and operation of 
individual designs. Circuits, amplifiers, and associated equipment and methods 
are illustrated and described. 

Four interesting articles present a lucid picture of what goes on behind the 
scenes in the film processing laboratories and in the editing and assembly rooms. 

Articles on acoustics give an idea of the problems encountered by acoustical 
engineers in the building of studios and theaters. Little is known regarding 
this phase of the art by the average person, and these articles give some very 
interesting information. 

The projecting and reproducing of sound motion pictures is explained in 
articles on both the Western Electric and the RCA Photophone systems. 

The book is well ended by a glossary of motion picture terms used in the 
laboratories, the studios, and the theaters. 


Patent Law. FRED H. RHODES. McGraw-Hill Book Co., New York, N. Y., 
1931, 207 pages. 

This book is highly recommended to everyone coming even remotely in contact 
with patents and inventions. The work is easily read, but is surprisingly compre- 
hensive. Most of the points with which the layman, and especially the inventor, 
should be familiar, are covered. 

There is a brief resume of the development of patent law. Other chapters 
cover in a concise and clear manner what persons are entitled to a patent, the 
differences between invention and discovery, and what constitutes novelty and 
patentability. Several sections deal with the application and the obtaining 
of the patent itself. The principal points covered here are the date of invention, 
abandonment, the form of the application, and the prosecution and amendment 
of the application. Other chapters deal with the legal aspects of a patent after 
it has been granted. These include a chapter on the rights conferred by a patent, 
a chapter on infringement, and another on testing the validity of a patent. A 
closing section deals with the rights of employers and employees, and the policy 


in respect to patents generally. An index of citations is included and a subject 

The language is non-technical and the style direct and clear. As indicated 
at the beginning of the book, it is written especially for chemists, inventors, 
and executives. It is one of the best of such works. 




J. I. CRABTREE, Eastman Kodak Co., Rochester, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 


K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westhighouse Lamp Co., Bloomfield, N. J. 

H. T. COWLING, Eastman Teaching Films, Inc., Rochester, N. Y. 

Board of Governors 

F. C. BADGLEY, Canadian Government Motion Picture Bureau, Ottawa, Canada 
H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Rochester, N. Y. 
J. I. CRABTREE, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
K. C. D. HICKMAN, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 
J. E. JENKINS, Jenkins & Adair, Inc., 3333 Belmont Avenue, Chicago, 111. 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 
W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood Blvd., 

Los Angeles, Calif. 
M. W. PALMER, Paramount Publix Corp., 35-11 35th Ave., Long Island City, 

N. Y. 
L. C. PORTBR, General Electric Co., Nela Park, Cleveland. Ohio 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 












W. V. D. KELLEY, Chairman 



W. C. KUNZMANN, Chairman 

C. L. GREGORY, Chairman 




Membership and Subscription 
H. T. COWLING, Chairman 











O. M. GLUNT, Chairman 


D. McNicoL 


G. E. MATTHEWS, Chairman 














[J. S. M. P. E. 





Projection Practice 
H. RUBIN, Chairman 



P. A. McGuiRE 


Projection Screens 
S. K. WOLF, Chairman 


Projection Theory 
W. B. RAYTON, Chairman 




W. WHITMORE, Chairman 












H. B. SANTEE, Chairman 


Standards and Nomenclature 
A. C. HARDY, Chairman 


Studio Lighting 

M. W. PALMER, Chairman 






Aug., 1931] COMMITTEES 295 

Chicago Section 

J. E. JENKINS, Chairman R. P. BURNS, Manager 

R. F. MITCHELL, Sec.-Treas. O. B. DEPUE, Manager 

New York Section 

M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 

Pacific Coast Section 

D. MACKENZIE, Chairman G. MITCHELL, Manager 

E. HUSE, Secretary H. C. SILENT, Manager 

L. E. CLARK, Treasurer 


Batsel, C. N.: Born 1898, at Fulton, Kentucky. B.M.E., University of Ken- 
tucky, 1919; engineer, Empire Gas and Fuel Company, 1919-21; engineer, 
Tennessee Copper and Chemical Company, 1921-23; research engineering depart- 
ment, Westinghouse Electric and Manufacturing Company, 1928-30; RCA 
Victor Company, 1930 to date. 

Brackett, F. P.: Born June 16, 1865, at Provincetown, Mass. A.B., Dart- 
mouth College, A.M., Sc.D. Instructor, Mathematics and Astronomy, 1888- 
90; director of observatory, Pomona College, 1890 to date. Member 
Smithsonian Astronomical Expedition to Africa, 1911; Mt. Whitney Expedition, 
1913; director, Solar Eclipse Expedition to Isthmus, Santa Catalina Island, 1923. 
Editor, Astronomical Publication of Pomona College. 

Hardy, A. C.: See March, 1931, issue of JOURNAL p. 389. 

Kellogg, E. W.: Born 1881, at Vineland, N. J. C.E., Princeton, 1906, Civil 
Engineering, 1906-8; Cornell 1908-9; test engineer, Commonwealth Edison 
Company, 1909-10; instructor, electrical engineering, University of Missouri, 
1910-15; assistant professor, electrical engineering, A & M College (Texas), 1915- 
16; assistant professor, electrical engineering, Ohio State University, 1916-17; 
research laboratory, General Electric Company, 1917-30; engineering depart- 
ment, RCA Victor Company, 1930 to date. 

Kelley, W. V. D.: See April, 1931, issue of JOURNAL, p. 519. 

MacKenzie, Donald: Born December 20, 1887, at Weatherford, Texas 
Ph.D., Johns Hopkins University, 1914; assistant in astronomy, Johns Hopkins, 
1914-17; assistant and associate physicist, Bureau of Standards, 1918-20; 
engineer, Western Electric Company and Bell Telephone Laboratories, 1920-29; 
consulting engineer, Electrical Research Products, Inc., 1929 to date. 

Pineo, O. W.: Born September 27, 1908, at Katahdin Iron Works, Maine. 
S.B. in physics, Massachusetts Institute of Technology, 1929; assistant, depart- 
ment of physics, Massachusetts Institute of Technology, 1929 to date. 

Schlanger, Ben: Born November 20, 1904, at New York, N. Y. Beaux Arts 
Institute of Design, 1925; theater architect, 1925 to date. Co-author of Ameri- 
can Theaters of Today, Part II. 

White, D. R.: Born at Berea, Ohio. B.S., Baldwin-Wallace College, 1922; 
Ph.D., physics, Columbia University, 1927; sensitometric and research work, du 
Pont Pathe Film Manufacturing Corporation, 1927 to date. 




DRESDEN, AUGUST 3-8, 1931 

For the first time the International Congress for Photography is to 
be held in Germany. Plans for the Congress are in the hands of an 
active committee composed of well-known representatives of photo- 
graphic research. 

Professor Albert Einstein as honorary chairman will open the 
Congress with a lecture. 

The activities of the Congress comprise four sections: 

I. Photography 

(a) Theoretical principles 
(6) Practical photography 
1 1 . Cinematography 

III. Application of photography and motion pictures to science and engi- 

IV. History, bibliography, legal problems 

In conjunction with the Congress an exposition of apparatus and 
the most recent results of scientific photographic research will be held. 

Lectures which have been announced so far include the following 
subjects: sensitometry, latent-image, cinematography, color pho- 
tography, astronomy, medical and x-ray photography, sound film, 
technic of reproduction, history of photography, etc. 

The large program of lectures will offer an opportunity to obtain 
the most recent information regarding all branches of photographic 
research. Among others, Professor Dr. Eggert of Leipzig will speak 
on the color film; Professor Dr. Freundlich, Potsdam, on photog- 
raphy in astronomy; Professor Dr. Goldberg, Dresden, on the 
experimental principles of the sound film; Professor Hertzberg, 
Stockholm, on the pictures of the Andree expedition; Professor 
Ponzio, Turin, on photography in medicine and x-ray technic; 
Dr. S. E. Sheppard, Rochester, U. S. A., on the latent-image; and 
Joris Ivens, Amsterdam, on present and future artistic problems of 
musical film with demonstration of an international selection of 
particularly representative films. 



The Congress, therefore, will be of great interest to all who work 
with any branch of photography. 

Beautiful Dresden, with its wonderful environment, is a suitable 
setting for this convention and many delegates to the Congress may 
wish to make use of the opportunity to spend their vacations 

A varied entertainment program will be of interest to the dele- 
gates. Among other things the delegates will have an opportunity 
to inspect the sound film studio of Ufa and to observe a sound film 
recording on August 8th in Berlin, Neubabelsberg. 

President Crab tree has appointed Dr. S. E. Sheppard as official 
delegate to represent the S. M. P. E. at this Congress. 


The binder shown in the accompanying illustration serves as a 
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The separate copies are held rigidly in place but may be removed or 
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These binders may be obtained by sending your order to the 
General Office of the Society, 33 West 42nd Street, New York, N. Y., 
accompanied by a remittance of $2.00. Your name and the volume 
number of the JOURNAL may be lettered in gold on embossed bars 
provided for the purpose at a charge of $0.50 each. 



There is mailed to each newly elected member, upon his first 
payment of dues, a gold membership button which only members 
of the Society are entitled to wear. This button is shown twice 
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Associate members of the Society may obtain the membership 
certificate illustrated below by forwarding a request for the same to 
the General Office of the Society at 33 W. 42nd St., New York, N. Y., 
accompanied by a remittance of $1.00. 

Society /Motion Picture Engineers 



Society of Motion Picture Engineers 

lO, 031 



[J. S. M. P. E. 



Asanuma & Co., 16 Honcho Nichome, 
Nihonbashi-ku, Tokio, Japan. 

3706 N. Charles St., Baltimore, Md. 


Regent Theater, Gisborne, New Zea- 


Western Electric Co. of Brazil, 
Praza Ramos de Azevedo 16, Sao 
Paulo, Brazil. 


Lignose-Horfilm, Lindenstr. 32-34, 
Berlin, S. W. 68, Germany. 


Warner Bros. Theaters, Inc., 321 W. 
44th St., New York, N. Y. 


Metro-Goldwyn-Mayer Studios, Cul- 
ver City, Calif. 

Pathescope Co. of America, Inc., 33 
W. 42nd St., New York, N. Y. 


101 Liberty Ave., Mineola, L. I., 

N. Y. 

151 Wainui Road, Kaiti, Gisborne, 
New Zealand. 


Kodak Japan, Ltd., 3-Nishiroku- 
chome, Ginza, Tokio, Japan. 


Multicolor, Ltd., 7000 Romaine 
Blvd., Hollywood, Calif. 

Harriscolor Films, Inc., Concourse 
Bldg., Jersey City, N. J. 


United Artists Corp., 729 Seventh 
Ave., New York, N. Y. 


411 Hankow Road, Shanghai, China. 


Consolidated Amusement Co., Hono- 
lulu, Hawaii. 


J. Osawa & Co., Ltd., San jo Kobashi, 
Kyoto, Japan. 


4538 Denny Ave., North Hollywood, 


1125 Cleveland Ave., N. W., Can- 
ton, Ohio. 

P. O. Box 650, Miami, Fla. 


Research Laboratory, Eastman Ko- 
dak Co., Rochester, N. Y. 


C. L. Venard Studios, 702 South 
Adams St., Peoria, 111. 


RCA Photophone, Inc., 411 Fifth 
Ave., New York, N. Y. 


Carrier Engineering Corp., 748 E. 
Washington St., Los Angeles, 


Paramount Publix Corp., 36th St. & 
Pierce Ave., Long Island City, N. Y. 


Paramount Publix Corp., 5451 Mara- 
thon St., Hollywood, Calif. 

* (AT) indicates active grade; (A) associate grade. 



Dunning Process Co., 932 No. La RCA Photophone, Inc., 142 Wardour 

Brea Ave., Hollywood, Calif. St., London, W. 1., England. 


H. KEITH WEEKS (M} Owens Development Corp., 40 W. 

Fox Film Corp., Beverly Hills, Calif. 13th St., New York, N. Y. 

J. E. SMITH (M), National Radio Institute. Washington, D. C. 




Agfa Ansco Corporation 

Bausch & Lomb Optical Co. 

Bell Telephone Laboratories, Inc. 

Carrier Engineering Corp. 

Case Research Laboratory 

DuPont-Pathe* Film Manufacturing Corp. 

Eastman Kodak Co. 

Electrical Research Products, Inc. 

General Theaters Equipment Co. 

Mole-Richardson, Inc. 

National Carbon Co. 

Paramount Publix Corp. 

RCA Photophone, Inc. 

Technicolor Motion Picture Corp. 


Prior to January, 1930, the Transactions of the Society were published quar- 
terly. A limited number of these Transactions are still available and will be 
sold at the prices listed below. Those who wish to avail themselves of the op- 
portunity of acquiring these back numbers should do so quickly, as the supply 
will soon be exhausted, especially of the earlier numbers. It will be impossible 
to secure them later on as they will not be reprinted. The cost of all the available 
Transactions totals $46.25. 


Price No. 


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1918 7 




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Beginning with the January, 1930, issue, the JOURNAL of the Society has been 
issued monthly, in two volumes per year, of six issues each. Back numbers of all 
issues are available at the price of $1.50 each, a complete yearly issue totalling 
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Orders for back numbers of Transactions and JOURNALS should be placed 
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and should be accompanied by check or money-order. 




Volume XVII SEPTEMBER, 1931 Number 3 



Recent Contributions to Light Valve Technic . . O. O. CECCARINI 305 

A Sound Film Re-recording Machine J. J. KUHN 326 

Motion Picture Screens Their Selection and Use for Best 

Picture Presentation FRANCIS M. FALGE 343 

Symposium of New Motion Picture Apparatus 363 

Recording on Sound Stages with Portable Units 

Standardization of the Picture Aperture and the Camera Motor 

A Needed Development FRED WESTERBERG 395 

A Note on the Need for Re-designing the Auxiliary Camera 

View-Finder FRIEND F. BAKER 398 

The Camera of Tomorrow IRA B. HOKE 401 

Problems of the Cameraman LEWIS W. PHYSIOC 406 

Banquet Speeches Hotel Roosevelt, Hollywood, Calif., May 

27, 1931 417 

Committee Activities: 

Report of the Committee on Standards and Nomenclature . . 43 1 

Report of the Projection Screens Committee 437 

Report of the Historical Committee 448 

Early Film and Telegraphone Demonstration at the Holly- 
wood Convention 450 

Report of the Membership and Subscription Committee .... 452 

Abstracts 455 

Patent Abstracts 462 

Book Review 468 

Officers 469 

Committees 470 

Contributors to This Issue 473 

Society Announcements 474 

Fall Convention, Arrangements Program 479 

Open Forum 485 





Associate Editors 




Published monthly at Easton, Pa., by the Society of Motion Picture Engineers 

Publication Office, 20th & Northampton Sts., Easton, Pa. 
General and Editorial Office, 33 West 42nd St., New York, N. Y. 

Copyrighted, 1931, by the Society of Motion Picture Engineers, Inc. 

Subscription to non-members, $12.00 per annum; to members, $9.00 per annum, 
included in then- annual membership dues; single copies, $1.50. A discount 
on subscriptions or single copies of 15 per cent is allowed to accredited agencies. 
Order from the Society of Motion Picture Engineers, Inc., 20th and Northampton 
Sts., Easton, Pa., or 33 W. 42nd St., New York, N. Y. 

Papers appearing in this Journal may be reprinted, abstracted, or abridged 
provided credit is given to the Journal of the Society of Motion Picture Engineers 
and to the author, or authors, of the papers in question. 

The Society is not responsible for statements made by authors. 

Entered as second class matter January 15, 1930. at the Post Office at Easton, 
Pa., under the Act of March 3, 1879. 


Summary. This paper describes structural changes made in light valves with 
the object of improving their quality, stability of operation, and efficiency, the most 
important being the introduction of damping to of -set resonance. These features 
are chiefly considered from the standpoint of production requirements and engineering 
economies. The shapes of the exposure waves for the two outstanding types (single 
and double ribbon) are considered. A new type of oscillograph (synchronous slit 
type) is described. This oscillograph permits the behavior of the valve to be observed 
at any frequency within the recording range. 

The apparatus which is most likely to receive the greatest possible 
attention in the way of improvements by the operating personnel, is 
that which seems inherently too delicate to stand the hardship of mo- 
tion picture sound recording. 

No apparatus is too delicate for use in the physical laboratory, but 
when it is sent out into the field, applied to production, and handled 
by less skilled personnel, it -must often be substantially remodeled, 
divested as much as possible of its weak features, and its economic 
performance must be assured. This transformation is sometimes 
prevented by a too great demand for immediate practical application ; 
improvements must then follow as dictated by practice. 

The original form of the light valve as applied to recording sound on 
film could have been substantially so described without doing injustice 
to pioneers in this particular field. It was very delicate, and it had a 
natural period within the useful recording range. The exposure wave 
was appreciably distorted at high frequencies, and the delicate ribbons 
when vibrating did not move in an absolute plane, but had a tendency 
to rock a great deal, and occasionally would touch the pole piece if 
the height of the ribbon were not properly adjusted. 

The light valve was, beyond doubt, and probably still is the weakest 
link in the chain of the recording apparatus. It has received consid- 
erable attention in the laboratories and studios, and genuine efforts 

*Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
**Metro-Goldwyn-Mayer Studios, Culver City, Calif. 


306 O. O. CECCARINI [j. s. M. P. E. 

have been made toward the elimination of its undesirable 

It will be interesting to review the various changes made in chrono- 
logical order. 

Fig. 1 is a schematic representation of the original form of light 
valve when first applied to the recording of sound on film. The two 
ribbons tend to move apart under the applied tension, but are pre- 
vented from doing so by four metal springs which permit correct 
adjustment of each ribbon with respect to the other, and also with 
respect to the light passage through the pole piece. The ribbons 
rest on bakelite bridges which act also as insulators. The length of 
the vibrating section in each ribbon is approximately 7 / 8 inch, and 
originally it was recommended to tune the valve to 7,000 cycles. 

One of the chief difficulties encountered was the shifting of the 

FIG. 1. Form of light valve first applied to the recording of sound on film. 

ribbons upon the bakelite bridges as a result of heavy impulses, the 
restoring force apparently being insufficient to overcome the friction 
between the ribbons and the bridges and, therefore, causing a per- 
manent change of the ribbon spacing. As a result of this difficulty 
valves had to be checked very frequently. 

The resonance peak occurring at 7,000 cycles was also found to be a 
source of trouble. This frequency is well within the accepted range, 
and the equalizer used to offset the abnormal response of the valve at 
that frequency did not prove entirely satisfactory. 

Two important changes then appeared highly desirable: a means 
for preventing the ribbon from losing its correct adjustment, and 
the shifting of the tuning frequency to an appreciably higher value 
without an effective increase in tension. 

Luckily, a very simple expedient presented itself for accomplishing 
both objectives at the same time. It consisted in gluing the ribbons 


between insulating spacers in the manner shown in Fig. 2. These 
spacers were conveniently cut from paper 0.002 inch thick and mea- 
suring approximately 0.040 inch by 0.080 inch. The mode of pro- 
cedure was very simple, as these spacers were applied after the valve 
had been correctly spaced and tuned to 7,000 cycles as under ordinary 
conditions. This amounted to shortening the vibrating loop from 7 / 8 
to about I1 /i6 inch, and as a result, the frequency of resonance 
changed from 7,000 to about 9,000 cycles without having to increase 
the effective tension; and the ribbons being definitely clamped with 
respect to each other, would remain correctly adjusted throughout 
their entire life. 

FIG. 2. Showing manner in which ribbons are glued between insulating spacers. 

The general improvement of quality in the high frequency range 
was found to be considerable, and the advantage of a higher tuning 
frequency was soon recognized. We began to use paper spacers in 
January, 1929, and, several months later, Electrical Research Prod- 
ucts, Inc., introduced a new valve with an appreciably shorter 
vibrating loop, although the insulating paper spacers seem to have 
been an exclusive feature of the valves used at the Metro-Goldwyn- 
Mayer Studios. 

The amplitude of the resonance peak, ordinarily found in properly 
adjusted valves, is of the order of 16 to 18 db. above the normal re- 
sponse, or in amplitude ratio we might say that the valve at reson- 
ance would vibrate with an amplitude varying from 6 to 8 times 
greater for the same driving power than at other frequencies. 

The above values show that very little force is required to clash 



[J. S. M. P. E. 

the ribbons at resonance, and experience has amply proved that valve 
ribbons are broken under clashing conditions. A too high resonance 
peak, therefore, constitutes a hazard in the life of the valve, and al- 
though it can occasionally be tolerated from the standpoint of quality, 
we must realize that when a valve is broken during a "take," it means 
loss of time, which in effect is a financial loss. The usual mixer's 
practice is that of setting the level during rehearsal. But it is seldom 

FIG. 3. (a) Oscillogram of wave of 1,000-cycle tuning 
fork; (6) wave observed through synchronous slit oscillo- 
graph when wave (a) is applied to a light valve resonating 
at 9,000 cycles. 

that the actual volume during the take is an exact replica of the re- 
hearsal. Additional takes are not economically justified unless the 
discrepancy between the rehearsal and the take has been so great as 
to render the sound record useless. 

There are occasions when the dialog is mixed with special effects, 
such as gun shots, and the action is such that a composite sound record 
is impossible. The dialog is usually important, the gun shots simply 
adding dramatic effects. Obviously, the dialog must be intelligibly 



recorded, with the result that the valve is badly overloaded by the 
gun shots. 

Let us look briefly into the quality problem. Fig. 3 (a) represents a 
1,000-cycle wave from an electrically driven tuning fork. This wave 
is the trace of a curve obtained from a cathode ray oscillograph, and 
no distortion is introduced by the oscillograph. The wave is far 
from pure, and a mathematical analysis would show the presence of a 
ninth harmonic, in addition to other components. 

When this wave is applied to a light valve resonating at 9,000 
cycles, its mode of vibration as observed through a synchronous slit 





FIG. 4. (a) Response characteristic of light valve resonating at 9,000 cycles, 
operated by oscillator having a slight second harmonic; (b) similar to (a), but 
with an additional fourth harmonic in the oscillator. 

oscillograph, described later, is that of Fig. 3 (b), which is quite differ- 
ent from that of Fig. 3 (a). 

Suppose we should decide to measure the response characteristic 
of such a valve with an oscillator having a slight second harmonic. 
We should get a curve such as shown in Fig. 4(a). The small peak at 
4,500 cycles is caused by the second harmonic, accentuated by the 
resonance sensitivity of the valve. In a similar way, if the oscillator 
had in addition a small percentage of the fourth harmonic, we should 
get a characteristic with a peak at 2,250, and so on (Fig. 4(6)). Since 
speech, music, and sounds in general are characterized by complex 



[J. S. M. p. E. 

waves of transient and semi-transient nature, a certain amount of 
distortion by the light valve must be expected. The distortion is 
noticeable especially when compared with sounds recorded by 
devices free from resonance features, and a large number of tests 
have very definitely proved such to be the case. 

It is fair to state that the idea of introducing some sort of damping 
originated from the necessity of increasing the safety limit of the 
valve and improving its high frequency response. 

A close inspection of the mechanical arrangement of a double ribbon 
light valve will immediately show the difficulty of introducing physi- 
cal damping, due to the fact that any fluid used would tend to flow 
between the ribbons by capillary action and give rise to all kinds of 



\ \ 











~/~^ ~ =r ~v] 



1 1 

Qb Q) 

1 1 

FIG. 5. Schematic arrangement of single ribbon light valve. 

troubles; and therefore it becomes highly desirable to eliminate one 
of the ribbons and operate the other with reference to a fixed knife 

The arrangement assumes the form shown schematically in Fig. 5. 
We might mention at this point that dry damping is impossible 
unless a totally different form of vibrator is adopted. The single 
ribbon valve is not new, but has been investigated at various times. 
When damping is taken into consideration, the single ribbon arrange- 
ment offers real possibilities. 

We have tested many damping substances and various methods of 
application. The necessary qualities suitable for damping can be 
deduced from simple primary considerations. The fluid should have 
such a nature as to act purely as a mechanical resistance ; its consis- 
tency must not change with changes of temperature, and the ingredi- 



ents must not separate in time. So far, the ordinary automobile cup 
grease has proved the most satisfactory. The method of applica- 
tion is clearly shown in Fig. 6. 

Another interesting feature of the single ribbon valve is that the 
ribbon and knife edge are located in different planes with respect to 

FIG. 6. 

Showing method of damping the single ribbon 
light valve, using grease cups. 

each other and, therefore, in case of overload the ribbon travels undis- 
turbed past the knife edge. This eliminates the danger of damaging 
the ribbon, and the resulting wave exposure is appreciably different 
than that obtained by the double ribbon arrangement under clashing 
conditions. Curves in Fig. 7 represent an 80-cycle wave under over- 


FIG. 7. (a) Overloaded 80 cycle negative produced with single ribbon valve; 
80 cycle negative produced with double ribbon valve under clashing conditions. 

load conditions for both types of valve, traced by means of a micro- 
photometer. The dip in the double valve record produced by clash- 
ing actually shows 9,000 cycles. The too wide slit of the micropho- 
tometer has suppressed this frequency. The general opinion in this 
studio is that the effect of overloading is appreciably less noticeable 



[J. S. M. P. E. 

with the single ribbon valve, probably due to the entirely different 
nature of the distortion in the two cases. 

Typical characteristics of undamped (double ribbon) and single 
ribbon damped valves are given in Fig. 8. It will be noticed that if a 
small capacity (0.1 /if) is shunted across the 500-ohm side of the re- 
peating coil, the frequency characteristic of the damped valve be- 
comes substantially flat up to 9,000 cycles. 

FIG. 8. Typical characteristics of undamped valve (double ribbon), and damped 

valve (single ribbon). 

The difficulty of maintaining correct spacing with bakelite bridges 
has become more acute with the use of superimposed direct current 
for background noise elimination. This kind of trouble has been 
called hysteresis, presumably from its analogy with magnetic hys- 
teresis. In addition, bakelite is quite susceptible to moisture and 
temperature changes, and although expansion and. shrinking did not 
prove troublesome with the double ribbon valve arranged with paper 
spacings because the thickness of the paper itself proved sufficient 



to keep the ribbon the correct distance above the pole piece with the 
single ribbon valve, bakelite is totally unsuitable as material for the 

As explained above, in the single ribbon valve the ribbon is located 
in a plane above the knife edge. The distance is 0.001 inch, and we 
have found it to be a serious task to maintain this dimension with ac- 
curacy because of the expansion and shrinkage of bakelite due to 
changes of atmospheric conditions. We have found a relief for this 
situation in substituting a metal bridge for the bakelite. 

It has been mentioned previously that the ribbons do not move in 
an absolute plane. This has been observed by means of a microscope 
fitted with a special objective. Due to the difficulties of arriving at 

FIG. 9. General arrangement of metal bridge valve. 

accurate measurements under such conditions, the following deduc- 
tions are offered solely as qualitative, and can be observed by any- 
one, provided, of course, that certain necessary precautions are taken. 
With damped valves no departure from the true plane is observed 
for normal level. Beyond overload, a slight departure from the true 
plane is observed below 2,000 cycles; there is no departure above 
2,000 cycles; it is noticeable again at the resonance frequency. In un- 
damped valves the departure from the true plane is noticeable at 
ordinary levels, and becomes excessive at and around resonance. 
Careful observations seem to indicate definitely that the damping is 
particularly valuable in maintaining the ribbon in the true plane. 
There are also indications that no two valves behave identically in 



[J. S. M. P. E. 

this respect. This is to be expected because the symmetry of dis- 
tribution of longitudinal stresses in the ribbon at the spacing springs 
depends largely on the surface conditions of the springs and of the 
edge of the ribbon. 

The general arrangement of the metal bridge valve is shown in 
Fig. 9. The method of supporting and guiding the ribbon might prove 
interesting. The arrangement permits a very accurate sideward ad- 
justment, and when the valve is properly set, the adjusting screws 
can be securely clamped. The correct height of the ribbon above the 
knife edge is obtained by a vertical adjustment permitted by a longi- 
tudinal slot through the bridge. 

It might seem at first glance that too many adjustments are pro- 
vided. But it must be readily admitted that it is far easier from a 

FIG. 10. Photograph of section of complete valve assembly. 

mechanical standpoint to provide an adjustable bridge rather than 
to fit the bridges individually to each valve. The metal bridges 
are isolated from the frame, and connections from the bridge to 
the binding posts are made by means of heavy copper wire. One 
end of the ribbon is fastened to one bridge, and the other end to a verti- 
cal post which is pivoted to the other bridge and which carries a flat 
spring for tuning purposes. Small taper pins are used. The sec- 
tional photograph, Fig. 10, gives in correct scale the complete 
assembly. One of the most interesting features is that the length 
of the ribbon employed is very slightly in excess of the useful vibrat- 
ing span. This represents a big saving, not in ribbon, to be sure, 
although four valves can be strung with the same amount of ribbon 
formerly used for one valve, but in electrical energy. 


To be exact, the effective length of the ribbon, as part of the elec- 
trical circuit, is precisely the vibrating length, because the gold-plated 
adjusting screws form at all times a definite electrical contact, thereby 
short-circuiting the excess ribbon beyond this point. From the elec- 
trical circuit standpoint the length of ribbon is 7 /s inch. 

With a repeating coil suitably wound for this type of valve, the level 
required to produce overload is approximately 9 db. less than that 
required for the double ribbon type with 0.002 inch spacing. There- 
fore, satisfactory performance can be secured with an amplifier of 
moderate power, a point of great importance when considering 
portable equipment. 

If, on the other hand, one chooses to make use of the standard re- 
cording channel set-up as it now exists, the above excess energy can be 
utilized for operating a valve of similar construction, but employing a 
very much stronger ribbon. Molybdenum seems to be a very happy 

We have experimented with molybdenum ribbon and have found 
it entirely satisfactory. The tension necessary for tuning it is about 
one-fifth that required to break the ribbon. This gives an idea of 
the margin of safety available. The energy which a 9 A, or bridg- 
ing amplifier, is capable of delivering under any abnormal conditions 
is not sufficient to melt the ribbon. Approximately 1.25 amperes 
is the maximum current carried by the particular molybdenum 
ribbon with which we have been experimenting, before it melts. It 
can be heated to a cherry-red color without apparent ill effect. The 
expansion coefficient is about one-fourth that of duralumin. These 
figures readily prove that a valve equipped with molybdenum is a 
permanent valve in the strict sense of the word. This is quite 
important, especially when the sounds to be recorded include gun 
shots, such as we had, for instance, in the recording of Big House. 
Under such adverse conditions, it is generally found that duralumin 
becomes permanently deformed, increasing the response which, in 
turn, adds to the trouble. No such difficulty has been experienced 
with molybdenum. The critical limit of molybdenum is greater 
than the power limit of the bridging amplifier. No harm can 
therefore be done to the molybdenum valve by overloading the 

The criticisms advanced against the single ribbon, short-length 
damped valve is that the presence of lumped resistance for damping 
contributes to the hysteresis, and that the effective exposure wave at 



[J. S. M. P. E. 

high frequencies is appreciably more distorted than in the case of the 
double ribbon valve. 

With regard to the first criticism, we can say that although the 
argument may be sustained from a theoretical standpoint, practice 
has shown that no such thing exists, within the range of measure- 
ments, for properly adjusted valves. 

As to the second criticism, it is true that the shape of the exposure 
wave obtained with the single ribbon valve is different from that ob- 

Single ribbon valve, 100 per cent light modula- 
tion, 1,000 cycles (or 2,000 cycles for 2:1 optical 

Single ribbon resulting 
















Double ribbon valve, 100 per cent light modu- 
lation, 1,000 cycles (or 2,000 cycles for 2 : 1 optical 

FIG. 11. Simple harmonic waves representing the position of the ribbon edges 
for different values of time; frequency 1,000 cycles per second. 

Double ribbon resulting 

tained with the double ribbon valve, but that the latter is better than 
the former one is an opinion hardly justified. Although the resulting 
transmission wave, as obtained from the positive film, is appreciably 
modified by diffusion and other phenomena of development, never- 
theless it might be of interest to discuss the shape of the exposure wave 
on the negative in both cases. 

We can arrive at the result in three ways: by straightforward mathe- 
matical analysis; by applying the method of finite differences; and 



graphically. The last method, the clearest one from a physical point 
of view, will be adopted. We will consider the extreme case of com- 
plete light modulation for 1,000, 5,000, and 10,000 cycles. 

In Figs. 11, 12, and 13, the simple harmonic waves represent the 
positions of the ribbon edges for different values of time. The straight 
lines represent the space-time graph of certain points, P , PI ... P n , 
on the film. For convenience it is assumed that events begin at time 
t when, in the case of the single ribbon valve, the edge of the ribbon 



^ 1 





















Single ribbon valve, 100 per cent light modu- 
lation, 5,000 cycles (or 10,000 cycles for 2:1 
optical reduction) 

Single ribbon resulting 




Double ribbon resulting 

Double ribbon valve, 100 per cent light modu- 
lation, 5,000 cycles (or 10,000 cycles for 2:1 
optical reduction) 

FIG. 12. Same as Fig. 11; frequency 5,000 cycles per second. 

just coincides with the knife edge, and with the double ribbon valve 
the ribbon edges are just about in contact with each other. The 
space-cycle intercept on the film is divided into equal parts, the 
beginning of each part being denoted by the points P , PL . .P n ____ 
It is assumed that the point P on the film enters the light field at t . 
Evidently the time of exposure of each point is the projection of the 
space-time graph of the point not covered by the ribbons upon the 
time axis. 



[J. S. M. P. K. 

The resulting exposure wave in arbitrary units for the single and 
double ribbon valves is given in each figure. 

In the case of the single ribbon valve the above-mentioned wave 
exposure at 1,000 cycles for 100 per cent modulation presents a 
theoretical 17 per cent second harmonic as compared with 3.5 per cent 
in the case of the double ribbon. At 5,000 cycles, conditions are 
appreciably reversed, as the double ribbon valve in this case has a 
theoretical second harmonic of 55 per cent, and the single ribbon 40 
per cent. There must be a frequency between 1,000 and 5,000 cycles 







k s 



Single ribbon valve, 100 per cent light 
modulation, 10,000 cycles (or 20,000 
cycles for 2 : 1 optical reduction) 

Single ribbon resulting 































*.*. 7MT + 

Double ribbon valve, 100 per cent 
light modulation, 10,000 cycles (or 
20,000 cycles for 2 : 1 optical reduction) 

FIG. 13. Same as Fig. 11; frequency 10,000 cycles per second. 

Double ribbon resulting 

for which the two types of valve have an equal theoretical amount 
of second harmonic. The amplitude of the fundamental is always 
greater for the single ribbon valve. 

The above data are based on the consideration that the film actually 
perceives the same size of slit as formed by the ribbons, but as a matter 
of fact, an optical system is interposed between the valve and the film, 
and the scale of reduction produced by this system is in the ratio of 
approximately 2 to 1. 

Effectively, this means doubling the nominal frequency as indicated 
in the curves shown above, or in other words, what we indicate as 



1,000 cycles becomes 2,000 cycles; 5,000 cycles becomes 10,000 cycles, 
and so on. By this argument, we find that the second harmonic of 
the 1,000-cycle impressed wave, in the case of a single ribbon valve, 
is only of the order of 8 or 9 per cent, which checks exactly with actual 
measurements on positive film by means of electrical circuits. When 
the single ribbon valve begins to produce a second harmonic of 
serious amplitude the frequency of this harmonic is well beyond the 
useful frequency range, and the point that the single ribbon valve 
is not substantially inferior to the double ribbon valve is therefore 
justified. The 10,000-cycle exposure wave which, in effect, becomes 
20,000 cycles when the optical reduction is taken into consideration, 
is given only as a curiosity. 


FIG 14. Schematic set-up of synchronous slit oscillograph. 

The foregoing proves definitely that the advantages of the single 
ribbon light valve are chiefly mechanical, readily permitting the in- 
troduction of damping which, in turn, is desirable from the standpoint 
of over-all quality. 

Over a period of a year, a large number of comparative records 
have been made with both types of valve, and invariably the single 
ribbon damped valve has proved superior from the standpoint of 
naturalness and pleasing quality, and we are satisfied with its per- 
formance beyond any doubt. 

Incidentally, a certain percentage of the so-called high frequency 
film transfer loss should be definitely attributed to the light valve. 

There are occasions when the exact overload point of a valve 

320 O. O. CECCARINI [j. S. M. P. E. 

must be known quite accurately. Such information is necessary for 
correctly setting the bias equipment for eliminating background 
noise. Also, a knowledge of the efficiency of the valve at various 
frequencies is quite often desirable, or a comparison between two types 
of valves might be a subject of fundamental importance. 

All these questions can be immediately settled by the aid of the 
synchronous slit oscillograph. This device represents an application 
of well-known principles, and permits observing directly the behavior 
of a valve under exact working conditions without the aid of photo- 
electric cells, amplifiers, etc., and at any frequency within the audio 
range. The schematic set-up is shown in Fig. 14. 

For visual observations the scanning disk speed can be controlled 
by hand, and the wave can be held sufficiently stationary on the 
screen for all practical purposes. When a permanent photographic 
record is required, the speed of the scanning disk must be synchronized 
with the frequency exciting the valve. There are many ways of 
accomplishing this, which will not be described here. 

This oscillograph is being used in our studio at present for routine 
work. When a new ribbon is fitted to a valve the spacing adjustment 
is carried out under the microscope in the usual way, the tuning is 
done by the absorption method as described on another occasion, 1 
the damping is applied, and the efficiency is checked with the oscillo- 
graph. This procedure assures valves of extremely close adjustment, 
the deviation from the average being rarely in excess of 0.5 db. 

The discussions and opinions outlined in this paper are the results of 
experience in recording sound on film at the Metro-Goldwyn-Mayer 
Studios over a period of time extending from September, 1928, to date. 
Whether or not these results have any resemblance to those ob- 
tained in other studios we do not know, nor is it an easy matter to 
find out. 

In deciding upon changes in our recording technic we have always 
taken into consideration important economical factors in addition 
to quality, as we feel that quality must be achieved in the most eco- 
nomical manner in order to represent a real compromise. Obviously, 
in the matter of economics, the limitations of the reproducing ap- 
paratus in the theater field have been also taken into consideration. 

It is also a fact that in this studio alone, twenty-five million dollars 
a year are placed at the mercy of the valve. We feel, therefore, justi- 
fied hi carrying out investigations of any nature, the results of which 
will assure a more uniform and more dependable product. 




1 CECCARINI, O. O.: "The Measurement of Light Valve Resonance by the 
Absorption Method," /. Soc. Mot. Pict. Eng., XV (July, 1930), No. 1, p. 60. 


MR. SILENT: A single ribbon light valve having many similarities to the present 
day valves was developed by the Bell Telephone Laboratories in 1924 for the sys- 
tem of telephotography which is now in general use in this country.* For sound 
recording the double ribbon light valve was adopted in preference to the single 
ribbon valve after giving due consideration to the characteristics of both types. 
The relative amount of harmonic distortion introduced by the two light valves 
was a determining factor. Referring to Fig. 1 (of this discussion), the curves 
numbered 1, 2, and 3, represent the fundamental, second, and third harmonics, the 
"S" and "D" referring to single and double ribbon, respectively. It will be noted 





4000 6000 


FIG. 1 (of discussion). Frequency components in exposure 
wave of single and double ribbon light valve. 

that the amount of fundamental in the exposure wave drops off only about 1 db. 
for the single ribbon valve and 1.5 db. for the double ribbon valve at 6,000 cycles. 
However, the amount of harmonic distortion is considerably greater for the single 
ribbon light valve than for the double ribbon type at all points below about 9,000 
cycles. Above this frequency harmonics are obviously of no importance. At 
around 1,000 to 2,000 cycles the second harmonic of the single ribbon valve is ap- 
proximately 15 db. greater than that of the double ribbon valve. This represents 
approximately 25 times more distortion power in a record made with the single 
ribbon valve than in one made with the double ribbon type. The third harmonic 
of the single ribbon valve is also considerably greater than that of the double 
ribbon type. Practically, therefore, while we may safely say that neither type 
of light valve causes appreciable loss at high frequencies, the fidelity of the sound 
record produced by the double ribbon valve is considerably superior to that pro- 

* IVES, H. E., HORTON, J. W., PARKER, R. D., AND CLARK, A. B.: "Trans- 
mission of Pictures over Telephone Lines," Bell System Tech. J., 4 (April, 1925), 
No. 2. 

O. O. CECCARINI [j. S. M. P. E. 

duced by a valve with a single ribbon. The mathematics of the curves have brrn 
independently developed by a number of different investigators, but being rather 
lengthy, are omitted here. Although there is considerable in favor of the double 
ribbon valve from these considerations alone, other points are cited below. 

A second reason why the double ribbon valve was chosen instead of the single 
ribbon valve concerns the power required to operate the valve. For a particular 
set of structural dimensions, it takes twice as much power to modulate a single 
ribbon valve as a double ribbon valve. This has a direct bearing on the develop- 
ment of portable equipment. 

It is not ordinarily regarded as good practice to allow the light valve to clash, 
nor is valve clash an inaudible thing, but if a light valve inherently degrades the 
quality, the clash or overload will be less noticeable than if the system be of high 
quality throughout. With every effort being directed toward obtaining higher 
quality, no sacrifice can be acceptable which cancels these efforts. In analyzing 
actual sound records, visual inspection of the wave form is not only inadequate, 
but may be misleading. A badly overloaded record may not appear so by visual 
inspection. It is necessary to use a positive record and subject it to accurate 
quantitative analysis, since the negative bears a reciprocal relationship to the 
original wave form and is not used for reproduction in the theater. 

While the light valve appears to be delicate when we consider some of its almost 
microscopic dimensions, it is a rather reliable piece of equipment, as is attested to 
by the millions of feet of sound film which have been produced by it, under any 
and all kinds of operating conditions, with relatively few failures. It is proving 
to be a surprisingly rugged piece of equipment. The use of various materials for 
the ribbon has been carefully studied. Using the constants given in Kent's 
Handbook for Mechanical Engineers for ribbons of duralumin and of molybdenum 
of the same cross-sectional area, it will be found that a light valve strung with 
duralumin can be tuned to a frequency 36 per cent higher than one strung with 
molybdenum, for the same factor of safety against breaking. In addition, the 
weight and resistance of the duralumin ribbon is inherently less than ribbons of 
other suitable materials, so that considerably less power is required for modu- 
lating. In the matter of the mechanical construction of the light valve, the 
fewer the adjustments necessary to apply to the valve, the better the construction 
the valve may be said to have. Obviously, it is not desirable to make extensive 
adjustments in the field if these can be eliminated by a little different mechani- 
cal design. 

It sometimes appears that certain devices are developed independently of the 
laboratories' recognition of their need, when actually the laboratory anticipated 
the need and worked toward the provision of the device long before its appearance 
in the field. For instance, the need of higher tuning of the light valve was recog- 
nized by the laboratories in their original design, and the original light valve was 
tuned to a considerably higher frequency than 7,000 cycles. Regrettably, the 
strength of the light valve ribbon produced in quantity was inferior to that ini- 
tially produced in small numbers. The tuning frequency, accordingly, had to be 
reduced. A shorter bridge light valve to correct this condition was brought into 
the field as soon as the necessary tests had fully proven it to be entirely satis- 
factory. The short bridge valve was generally adopted by the studios in both 
Hollywood and in the East and was found to be satisfactory. There have been 


other improvements since, and more are being made. The gummed label valve 
was never approved because of its unsatisfactory performance. 

The use of greases and oils intended for automobile lubrication cannot at present 
be regarded as satisfactory for the service of damping light valve ribbons. At 
best their contribution to the damping of the valve cannot offset the factor of 
uncertainty of action which they introduce. By properly tuning the valve to a 
frequency higher than any it is required to record there is no need for such damp- 
ing. The apparent effects of peaked response of the valve below the tuning fre- 
quency are the results of harmonics of the oscillator which is used, and are not true 
phenomena of actual recording. 

MR. CECCARINI: It is rather unfortunate that sturdiness and ruggedness are 
relative. A device might be considered quite sturdy until it fails many times 
during production, and causes the loss of thousands of dollars. To the mind of 
the operating engineer, such devices cease to be sturdy, and become potential 
sources of trouble, although the opinion of the laboratory engineer might remain 

Upon inquiring of our purchasing department, I find that since September, 
1928, we have bought 5,000 feet of duralumin ribbon. Dividing this amount 
equally among 900 working days, it appears that an average of a little more than 
five valves per day have been strung. It seems hardly fair to call the light valve 
sturdy, on the basis of these figures. 

The object of presenting the overload waves given in Fig. 7 of my paper is to 
show the action of the two types of valve under overload conditions, and for this 
purpose the negative transmission tells the story better than the positive. 

It would be very convenient, indeed, to have a valve with all the adjustments 
made once for all, but unfortunately, the duralumin ribbon we have been getting 
has varied from 0.004 to 0.008 inch in width, and as long as these conditions exist 
we require adjustments, either in a crude form, or in the more precise fashion 
such as we have adopted. 

With regard to the amount of second harmonic generated by the single ribbon 
as compared with the double ribbon valve, Mr. Silent states that the difference 
between the two is of the order of 15 db. for 1,000 cycles impressed fundamental 
at 100 per cent light modulation. While this figure coincides with mine, and ap- 
pears correct in the abstract sense, it is nevertheless sadly misleading. It must be 
remembered that the amplitude of the second harmonic for the single ribbon valve, 
under the above conditions, is only of the order of 8 or 9 per cent of the funda- 
mental. This is a negligible quantity, especially when considered as applying 
to 100 per cent light modulation, which in itself, is an extreme condition. It 
therefore makes no difference how much lower is the second harmonic of the double 
ribbon valve, be it 15, or 50, or 100 db. The argument has no logical value. 
The power required to overload a single ribbon valve is, correctly, twice as great 
as that required for the double ribbon valve. The undistorted power which our 
recording amplifiers are capable of delivering is many times greater than the 
overloading power of any one type of valves. The limit of the film characteristic 
coincides with the power limit of the valve, at least as far as the negative is con- 
cerned, and the thought that beyond this limit the amplifier still continues to 
deliver undistorted power, which might help, is a meager and costly consolation. 
It does not seem reasonable, from the standpoint of engineering economics to 

324 . O. O. CECCARINI [J. S. M. P. E. 

make use of amplifiers of such excessive power capacity. In fact, some experi- 
ments which we conducted some time ago, with amplifiers having undistorted 
power capacity just slightly beyond that of the valve, have proved conclusively 
that they are of service under overload conditions, as they behave very much as 
power limiting devices, additional safeguards for the valve. After the wave 
shape is badly distorted by an overloading valve, very little, if any, additional 
distortion will be possibly introduced by an overloading amplifier. 

In addition, the power limit of the amplifiers provided in the standard channel 
is set for disk recording, and certainly there is no objection to utilizing a larger 
proportion of this power, which would ordinarily be dissipated through an artificial 

The molybdenum ribbon, which we have used and are using on special occasions, 
has proved to be much safer than the duralumin ribbon. Regarding the physical 
properties of a given metal or product, we always accept as correct the data fur- 
nished by the manufacturer. I can cite by the dozens, cases in which the dura- 
lumin valve broke, while the molybdenum valve never failed. Our contention is 
not that we have invented a single ribbon valve but rather that we have discovered 
in it valuable features, which, when properly taken advantage of, render it superior 
in practice to its double ribbon competitor. 

Cup grease fulfills the purpose of damping very well. The fact that it serves 
also to lubricate machinery has no bearing on the subject. Its purpose is to 
damp mechanical vibrations, not to lubricate. 

I would like again to emphasize the fact that the conclusions given in this paper 
were arrived at through a logical process of elimination, and that the experimental 
data were obtained over a long period of experimentation. 

MR. SHEA : It seems to me that this is a question of overload. It does not mat- 
ter what type of light modulating device is employed whether a glow lamp, 
galvanometer, single ribbon or double ribbon valve. If it is overloaded, distor- 
tion will result. If, at high levels the light valve is subjected to reasonable over- 
loads, I think it is a fairly rugged instrument. We have had light valves on labo- 
ratory test at 1,000 cycles with a continuous overload of 4 db. for as long as 1,000 

MR. MILLER: There is a big difference between laboratory work and commer- 
cial production. The normal recording level is well below the valve overload 
point. Occasionally, however, an unanticipated peak must be accommodated, 
and overload is apt to occur. The commercial problem is to attain a compromise 
between level and qualitv. The level must be high enough for the theater equip- 
ment, and the recording should be without objectionable surface noise. For these 
reasons we must accept some overloads, up to the point where they, also, produce 
no objectionable distortion. Every foot of film we make involves this com- 

MR. SHEA: If it is necessary in recording practice to meet these rather large 
overloads, you can retain the advantages of the double ribbon valve and get the 
advantages of the single ribbon valve by placing the two ribbons in different 
planes. This is done in the oscillagraph vibrator unit (the three-string valve) 
described at this afternoon's meeting, except that wires were used instead of 

MR. CECCARINI: In 1929 I made a valve such as Mr. Shea mentions, with the 


two ribbons located in slightly different planes. This valve did not prove prac- 

There seems to be a tendency to prove that it is not good practice to overload. 
I would like to call attention to some interesting facts published by Dr. Fletcher. * 
From the tables he gives we can readily deduce that if we were to record without 
any trace of overload, the average level of the record would be so low as to be of no 
commercial value. Obviously, we must strike a compromise by accepting a cer- 
tain amount of overload. It is fair enough, then, to use a device which produces 
the least noticeable overload effect, and which has, in addition, an ample margin of 

MR. LAMBERT: In the matter of overload there is one phase which, I am 
afraid, Mr. Shea and Mr. Silent did not know about. We made a German ver- 
sion of Big House. One of the actors had a very weak voice, and his voice was 
recorded along with the noise of machine guns. In preparing this for release we 
used a certain maximum fader setting which was customary with our releases 
and which our experience of more than a year had shown should not be exceeded. 
That fader setting was about 2 or 3 fader steps higher than the average fader set- 
ting. In order to get the effect we wanted in Big House we had to overload 
the valve considerably; we tried all the valves we had, including double ribbon 
valves of 1 and 2 mil separation which had been previously used in recording the 
American version of Big House with success. But on this one we broke all the 
double ribbon valves and all the single ribbon valves that had duralum in ribbons. 
The overloading due to the gun shot was required in order to force the dialog up 
to where we needed it. The overload point of the valve was +4 db., and the 
indicated levels in the valve on this recording were as high as +26 db. The only 
valve which withstood this treatment was strung with a single molybdenum rib- 
bon. During this recording we broke one ribbon and melted another, but ob- 
tained the record. 

* FLETCHER, H.: "Some Physical Characteristics of Speech and Music," 
Reviews of Modern Physics, 3, No. 2, p. 258. 

J. J. KUHN** 

Summary. In sound picture production, the process of making the release print 
negative for sound requires the reproduction of the existing positive sound record in 
order that it may be recorded in proper continuity and corrected for volume level. 
The machine used for this purpose is called a "re-recording machine." 

This paper describes a new re-recording machine recently made available which is 
suitable for use in studios using either the variable density or variable width method 
of recording sound. The machine described employs a novel type of film aperture 
and a new method of focusing the sound lamp. To insure uniformity of film move- 
ment and to eliminate unwanted noises in the re-recording process, the workmanship 
must be of the highest order. Some of the requirements and testing methods em- 
ployed in the manufacture of the machine are discussed. 

The first synchronous talking pictures produced were comparatively 
short subjects. They consisted of one or two reels which were built 
up of scenes or takes each of which was complete in itself. Conse- 
quently, it was then only necessary to patch such pieces of film to- 
gether in order to obtain a complete picture. Pictures obtained in 
this manner, of course, had many limitations and except for their 
novelty as talking pictures could not have been considered box-office 
attractions. The motion picture industry was, furthermore, too 
progressive to remain satisfied with such a product. 

As a result of the continued efforts of picture producers and of 
manufacturers of sound picture recording apparatus, the recording 
of sound to accompany pictures, as now produced, involves many 
practices which were formerly found effective in producing silent 
pictures. The most prominent of these is probably that employed 
in trick photography duping which in sound work has its counter- 
part under the title "dubbing." As noted previously in this JOUR- 
NAL, 1 dubbing may be simply the making of a sound record with the 
microphone to match a picture; it may be the combining of sounds 
picked up by the microphone with one or more sound records already 

* Presented in the Symposium on Sound Recording at the Spring, 1931, 
Meeting at Hollywood, Calif. 

** Bell Telephone Laboratories, New York, N. Y. 



made; it may be the combining of sound records only; or it may be 
simply re-recording an existing record. The last-mentioned has three 
principal purposes: 

(1) To make a new master record. 

(2) To transfer a record from film to disk or vice versa. 

(3) To correct volume variations and other sound effects. 

It is with respect to the machinery employed in reproducing sound 
film for the purpose of combining or re-recording sound records on 
film that this paper is concerned. 






FIG. 1. Front view of re-recording machine. 

Some of the requirements that a re-recording machine should be 
capable of fulfilling are: (a) the reproduction of a sound record on 
film should be a true copy of that record, and should not include addi- 
tional background noise ; (b) the film should move past the scanning 
light beam at a uniform speed, i. e., without flutter of the high-fre- 
quency or low-frequency type, usually referred to as "wow- wows;" 
(c) there should be no tendency for emulsion or wax from the film to 
deposit on the film gates or guides; (d) noise from the rotating parts 

328 J. J. KUHN [J. S. M. P. E. 

of the machine or vibration of the building should not be picked up by 
the speech circuit; and (e) the machine should be easy to thread, 
operate, and maintain. 

During the past year the Western Electric Company has made 
available to producers a re-recording machine which fulfills these 
requirements in a practical sense, and which includes a number of 
novel features. The front view of this machine is shown in Fig. 1 



FIG. 2. Rear view of re-recording machine. 

and the rear view in Fig. 2. It consists of a cast base upon which are 
mounted : 

(a) a sound reproducing head and magazine; 
(6) photoelectric cell coupling transformer; and 
(c) the driving motor. 

A panel for controlling and indicating the current through the sound 
lamp is mounted in the base. 

Sound Reproducing Head. The reproducing head consists essen- 
tially of a double-faced housing, the central partition of which pro- 
vides a common support for all associated units. This construction 



makes it possible to obtain a very rugged but easily accessible assem- 
bly. The housing at the front is the reproducing compartment, and 
the one to the rear is the gear case. 

Reproducing Compartment. Fig. 3 is a front view of the machine 
with the various compartments open to view. The drive shaft from 
the motor enters the rear of the case and drives two sprockets through 
suitable gearing. One of these sprockets is a combination pull-down 
and hold-back sprocket, and the other is the sound sprocket. These 


FIG. 3. Reproducing and lamp compartment. 

are the only two members inside the film compartment that are 
positively driven. 

The film magazine is located directly above the reproducing com- 
partment. The left-hand half of the magazine contains the supply 
reel and the right-hand half the take-up reel. The magazine is of 
sufficient size to accommodate either 1,000- or 2,000-foot film reels. 
Ample finger space is provided around the reels to simplify threading. 
The units are of cast aluminum rigidly bolted in place. The shaft 
supporting the supply reel operates against a friction drag which is 
adjustable at the rear of the magazine. The take-up reel is rotated 
by means of a friction drive geared to the motor shaft. 

330 J. J- KUHN [J. S. M. P. E. 

In the process of dubbing, it is frequently necessary to add noise 
effects or other sounds already recorded on a film. Where noise 
effects are of a more or less indiscriminate type, such as the clatter of 
horses' hoofs, wind noise, machine-gun fire, etc., they are usually 
recorded on short lengths of film, the ends of which are cemented 
together to form an endless loop. To accommodate such loops in 
the re-recording machine, a set of guide rollers is provided on top of 
the film magazine. 

Film Passage. The film coming from the supply reel is held in 
engagement with the pull-down sprocket by a double pressure roller. 
It then passes around an idler roller to a large drag roller. 

The film then passes upward through a roller type of sound aper- 
ture to the sound sprocket, thence to the combination pull-down and 
hold-back sprocket. On leaving the hold-back sprocket the film 
passes by a roller which is associated with a signaling device and 
onto the take-up reel in the film magazine. Excluding the pressure 
roller, all sprockets, guide-rollers, etc., in contact with the film are 
constructed of stainless steel. 

The roller type of sound aperture guides the film past the scanning 
lens which projects the image of a brightly illuminated slit upon it, 
the variations in the transmission of the film causing variations of 
the current through the photoelectric cell mounted behind it in 
accordance with the pattern on the sound track. 

Light for illuminating the slit of the lens system is obtained from a 
special ribbon filament lamp mounted in an adjustable holder. 

Drag Roller. The purpose of the drag roller is to impart a uniform 
tension to the portion of the film between the drag roller and the 
sound sprocket. It is constructed of stainless steel and is approxi- 
mately l 3 / 4 inches in diameter. Since the uniformity of the tension 
is determined by the constancy of rotation of the drag roller, it is 
important that the latter run absolutely true. Flanges are provided 
on each side of the roller to guide the film through the sound aperture. 

The drag roller is prevented from rotating freely by friction disks 
placed against the sides of the roller. These consist of a special 
alloy of bronze and graphite. The drag can be varied by adjusting 
the pressure of the compression spring on the outer face of the drag 

The film is held against the drag roller by means of a pressure 
roller. This roller is constructed of impregnated fabric, and is held 
under constant tension by means of a flat steel spring. 



Double Roller Aperture. As previously noted, the film between the 
drag roller and sound sprocket is held under tension while the machine 
is operating. To insure that the film remains in focus, at the same 
time applying as little pressure as possible against its face, rollers are 




FIG. 4. Double roller aperture. 







FIG. 5. Double roller aperture, side view. 

332 J. J. KUHN [J. s. M. P. E. 

placed in contact with the film at points directly above and directly 
below the scanning beam. The upper roller bears against the 
emulsion side of the film, while the lower roller bears against the base. 
This arrangement is clearly illustrated by Fig. 4, which also shows 
the location of the lamp with respect to the aperture lens unit and the 
focusing lens. A side view of the double roller aperture assembly is 
shown in Fig. 5. The rollers are made of stainless steel and rotate in 
jewel bearings. These are ground very accurately with respect to 
their bearing surfaces so that they will rotate freely without dis- 
placing the film. The bearing brackets supporting the jewelled 
rollers are dowelled in place so that they can be removed for inspec- 
tion and cleaning should this be found necessary. 

In Fig. 5, the sound track mask has been removed to show its 
general construction. This mask is provided so as to permit the 
beam of light to project only over the area of the sound track which 
it is desired to scan. This area can be equivalent to the full width 
of the sound track or can be adjusted so that only a portion of the 
sound track is scanned. 

Rollers are employed on each side of .the film rather than two 
rollers against the base side, as it was found that the latter arrange- 
ment required greater tension on the film to hold it in the focal 

A further advantage of the staggered rollers is that variations in 
the position of the film with respect to either of the rollers cause less 
movement of the film from its focal plane. For example, variations 
in the stiffness of the film cause it to pass over the rollers at a slightly 
varying radius. The staggered roller arrangement equalizes such 
variations, whereas, with two rollers on the same side the film will 
go out of focus to a rather large extent. Measurements on sample 
films in a test fixture under conditions approximating those employed 
in the re-recording machine show a very slight movement of the 
film from its focal plane when the film is maintained under the proper 
tension. This movement, incidentally, is of the order of the thick- 
ness of the emulsion and is not sufficient to cause noticeable variation 
in the sound output. 

Optical System. The aperture assembly provides a rigid mounting 
for the lens assemblies. The center one the aperture lens unit is a 
combination of condensing lens, slit, and the objective lens employed 
for focusing the scanning beam upon the moving film. A collective 
lens at the extreme left is provided for insuring that the light projected 



through the film falls on the active elements of the photoelectric cell. 
A third lens, shown at the extreme right, focuses an image of the lamp 
filament onto a ground glass cross-line screen and assists in simplifying 
lamp adjustments. A schematic arrangement of the optical system 
is illustrated by Fig. 6. 

The lamp employed is a 6-volt, 9-ampere ribbon filament lamp. 
The condensing lens in the aperture lens unit has a magnification of 








FIG. 6. Schematic arrangement of re-recording machine. 

unity and focuses the image of the filament onto a mechanical slit, 
flooding it with an intense light. The opening in this slit is held to a 
separation of maximum 0.0012, minimum 0.0009 inch. It is cen- 
trally located on the optical axis of the condensing and objective 
lenses, and the edges forming this slit are selected for smoothness and 
parallelism throughout their entire length. 

The objective lens is designed to give a 1.5 to 1 reduction of the slit, 
resulting in an image at the film plane 0.0007 =*= 0.0001 inch wide. 


[J. S. M P. E. 

In designing the lens system special care has been taken to provide 
an image that is uniformly illuminated throughout its length, and 
with clearly defined edges and a field free from flare. All lens assem- 
blies are inspected for accuracy and quality. 

The objective lens is adjustable to permit focusing of the unit. 
Movement of the lens unit is obtained by rotating the knurled 
head and locking it in place by a special lock nut. The lens unit is 
held in a rigid mounting having a double bearing, one of which is 
slotted to permit clamping the unit in place. Between the double 
bearing is a rotating collar which surrounds the lens unit, and 
provides a means for adjusting for azimuth. 














FIG. 7. Effect of adjustment of exciting lamp on volume output of 

The collimator lens is a small lens provided for insuring that the 
maximum amount of light transmitted through the film will be 
projected to the sensitive portion of the photoelectric cell. At the 
right of the illuminating lamp, a separate lens unit is provided for 
projecting an image of the lamp filament upon a ground glass screen 
located in the side wall of the lamp housing, thereby simplifying the 
adjustment and replacement of lamps in the field. When the system 
is first set up, the various units are adjusted with the aid of specially 
selected single-frequency films. The output of the photoelectric 
cell is connected to a suitable amplifier and volume indicator so that 
variations of response at different frequencies can readily be measured. 



The lens and lamp are adjusted to give the smallest difference in the 
scanning loss between the reproduction of a 1 ,000-cycle recording 
and that of a 7,000-cycle recording. A loss of approximately 1 db. 
is introduced for a 0.0007-inch scanning image and is due to the finite 
width of the scanning beam. 2 When these adjustments are ac- 
curately made, the lamp adjusting lens is then focused so as to 
project a sharp image of the lamp filament on the ground glass 
screen. The vertical and horizontal positions of the ground glass 
screen are then adjusted so that the cross-lines on this screen coincide 
with the center lines of the lamp filament. To adjust subsequent 
lamps it is only necessary to center the image of the lamp filament 
on the cross-line. This lamp adjusting lens system also shows when 
the lamp filament sags, thus indicating need for replacement. 

Lamp Adjustment. The sound lamp is provided with adjustments 
in all directions. This permits the attendant to obtain the best pos- 




FIG. 8. Focus of objective lens vs. quality of reproduction. 

sible results from his equipment. Contrary to the normal expecta- 
tion, however, the adjustment of the lamp is not as critical, in so far as 
quality of reproduction is concerned, as it may appear. As is illus- 
trated in Fig. 7A, an out-of-focus condition of the lamp approxi- 
mating 100 mils from the ideal horizontal position, or about 3 J /2 
turns of the adjusting screw, results in a loss of light projected on the 
film equivalent to 0.5 db. in volume. It is evident that the permis- 
sible variation of the horizontal adjustment of the lamp is greater than 
would ever be required. Fig. 7B shows a similar chart for vertical 
adjustment. Here a deviation of 18 mils, or 5 /s of a turn from 
normal, will result in a loss of about 0.6 db. When it is considered 
that the width of the lamp filament is over 30 times that of the 
mechanical slit to which it is adjusted, there should be no difficulty 
in adjusting the lamp in a comparatively short time. 



[J. S. M. P. E. 

An out-of-focus condition of the lamp affects the volume out- 
put a similar condition in the position of the objective lens affects 
the frequency response obtained through the film. As noted in Fig. 8, 
a change in the adjustment of the objective lens from its theoreti- 
cally correct position introduces a scanning loss in reproduction which 



FIG. 9. Cross-section of photoelectric cell and coupling transformer. 

varies with frequency. A variation of the position of the objective 
lens of one mil from the normal reduces the response at 7,000 cycles 
by only a fraction of a decibel. Since this lens is adjusted by the 
electrical method previously described it is not difficult to set the 
lens at its optimum position. If both the objective lens and the lamp 
are out of focus the total loss in decibels is the sum of the two losses. 



Photoelectric Cell and Transformer. The photoelectric cell is 
mounted in line with the collective lens and in such a position that the 
terminals of the cell are directly adjacent to the terminals of the 
transformer mounted directly in back of it. A cross-sectional view 
of the machine illustrating these units is shown in Fig. 9. 

The transformer has an impedance ratio of about 625 to 1, and was 
selected because it is as high as is considered desirable for reproducing 
a frequency band 10,000 cycles wide. The transformer is mounted 
in a cradle suspended on damped springs. This arrangement in- 
sures that vibrations either from the machine or from other sources 
in the building are not transmitted to the transformer and cannot, 






\f sp tzf SP 


J N 







O O 

-90 +90 


0.5 AMP 


FIG. 10. Schematic diagram of coupling transformer circuit. 

therefore, introduce noise into the recording circuit. The transformer 
unit is provided with a key by means of which the polarizing poten- 
tial of the photoelectric cell can be cut off. The circuit arrange- 
ment of the coupling transformer is illustrated in Fig. 10. The 
resistance, Ri serves as a protection for the polarizing voltage supply 
in case the terminals or elements of the photoelectric cell should 
become short-circuited and in conjunction with the condenser, C\ t 
niters out noise originating in the polarizing potential source. The 
resistance across the low side of the transformer stabilizes the im- 
pedance of the photoelectric cell output circuit. 

338 J. J. KUHN [j. s. M. P E. 

Excluding the scanning loss, the frequency response of the repro- 
ducing system, measured with a modulated light beam falling on the 
photoelectric cell, does not vary more than 1 db. at the output ter- 
minals for frequencies varying from 50 to 7,000 cycles. From 7,000 
cycles up, the characteristic rises slightly, reaching +2 db. at 10,000 

The relative output of the reproducing system using a lamp current 
of 9 amperes and a suitable amplifier is as follows: 

Output Level 
in Db. 

(a) 1,000 cycles, film transmission 30 per cent 

(6) unmodulated sound track 34 

(c) photoelectric cell illuminated by sound lamp through a clear part 

of stationary film but with machine running 57 

(d) photoelectric cell dark, machine not running 62 

It is evident from this data that the machine is capable of repro- 
ducing films having a volume range of 57 db., a value greatly in ex- 
cess of present-day practices. 

Driving Motor. The rear view of the machine, shown in Fig. .11, 
discloses a Vrhp., 1,200-rpm., 220- volt, 60-cycle interlocked driving 
motor, supported and cushioned on an adjustable plate. This plate 
is dovetailed in the bed of the re-recorder base so as to permit the end- 
wise withdrawal of the motor and the re-assembling of it without 
having to readjust it on its sub-base. In this way the motor driving 
shaft can be lined up with the corresponding shaft on the reproducing 
head by means of a tubular alignment sleeve, and the motor can be 
withdrawn to permit the insertion of the flexible couplings. These 
couplings are torsionally rigid but are flexible in a direction parallel 
to the shaft, thereby permitting a certain amount of end-play in 
the armature without transmitting this disturbance to the repro- 
ducing head. A switch is located on the base so that the motor can 
be shut off independently of the system when the film in its maga- 
zine has been completely reproduced. 

Gear Case. The shaft attached to the motor is provided with a 
stroboscope disk having 36 slots. The shaft then enters the gear 
case which contains the gearing necessary to reduce the motor speed 
of 1,200 rpm. to a speed of 360 rpm. at the sound sprocket and its 
filtered flywheel, and 180 rpm. at the combination pull-down and 
hold-back sprocket. Gearing is also provided to drive the take-up 
mechanism at the back of the film magazine. 



In order to insure a minimum of noise and vibration in the machine 
and that the film is propelled at a constant rate, it is necessary that 
all gears, sprockets, bearings, and their associated shafts be con- 
structed accurately. The entire gear housing is sealed against the 
leakage of oil. A gauge is provided so that the oil may be maintained 
at the proper level. 

Flywheel and Filter. As previously noted, the flywheel associated 
with the sound sprocket is provided with a filter. The filter used is 
of the spring type, suitably damped. The flywheel is statically 



FIG. 11. Rear view of re-recording machine. 

balanced in the factory and is again balanced after the entire machine 
is assembled. In this operation, the counterweights on the outer 
face of the flywheel are fastened in the required position so as to 
obtain the optimum balance of the entire assembly. The position 
of the counterweights is definitely indicated so that if they are at 
any time removed, they can be replaced in the correct location. 

The rim of the flywheel is graduated into 120 divisions, and the 
motor shaft is equipped with a shutter having 36 slots. The combi- 
nation of these two units comprises a very accurate stroboscope which 

340 J. J. KUHN [J. S. M. P. E. 

enables the recorder attendant to obtain a quick check as to whether 
the flywheel is rotating uniformly. 

In the testing of re-recording machines before leaving the factory, 
the uniformity of flywheel rotation is accurately checked against that 
of the stroboscope disk by a special microscope checking fixture. 
Because of the over-all requirements imposed, it is necessary that the 
spacing of the slots in the stroboscope disk and the lines on the face 
of the flywheel be extremely uniform. This spacing is done on special 

FIG. 12. Fixture for checking spacing of slots in stroboscope disk. 

machinery developed for the purpose and is checked on special 
fixtures such as are illustrated by Fig. 12 and Fig. 13. 

The stroboscope disk, A, is mounted on the shaft of a Carl Zeiss 
dividing head, C. Microscope, E, is adjusted so that its main hair- 
line coincides with one edge of the slot, B, appearing in the optical 
field. Microscope, F, is similarly adjusted and focused on the corre- 
sponding edge of the next slot. The angular reading in the eyescope, 
D, is noted and it is then indexed as 10 degrees. This operation 
brings a new slot into the field of each microscope and since the latter 
are calibrated in tenths-of -thousandths of an inch, the variation of 



spacing from the initial settings can be very accurately measured. 
As each new pair of slots is indexed the variation from the preceding 
set is noted and the final over-all error is computed. This total error 
is held within 0.001 inch for the 36 slots. A similar procedure is 
followed for checking the spacing of the slots in the flywheel 
(Fig. 13). 
These extraordinary efforts to obtain accuracy, while costly, are 

FIG. 13. 

Fixture for checking spacing of divisions on face of 

made to insure that all machines sent to the field will provide the high 
grade of service expected of them. Furthermore, the performance of 
the re-recording machines now in use at various studios amply justifies 
these efforts. In addition to fulfilling the basic requirements noted 
in the first part of this paper, the recording personnel finds that very 
little time is required to thread the film and set the machine into 

:?4i J. J. KUHN 


1 MORGAN, K. F.: "Scoring, Synchronizing, and Re-recording Sound Pic- 
tures," Trans. Soc. Mot. Pict. Eng. (1929), No. 38, pp. 268-88. 

* STRYKER, N. R.: "Scanning Losses in Reproduction," /. Soc. Mot. Pict. 
Eng., XV (Nov., 1930), No. 5, p. 610. 


MR. TOWNSEND: In most reproducing machines a fairly wide slit is used with 
a high reduction, the slit width being obtained by means of an optical system. 
Why in this particular case was it found better to use a small slit and a small 
optical reduction in the objective lens, in order to secure a light beam at the 
film 1 mil wide? 

MR. DAILY: The Bell Telephone Laboratories have made a thorough study of 
the efficiencies of various types of optical systems, and while I do not have at 
hand the comparative figures on this lens assembly as compared with others, 
I think it is as efficient as any available. A one mil slit is used between the con- 
densing and objective lenses with a 1.5 to 1 reduction in image width through 
the objective lens. Such a system has been found to be very satisfactory, giving 
a light field on the film of sufficient intensity and free from flare. 



Summary. Motion picture screens contribute very materially toward the success 
of a picture. A poorly selected or poorly used screen will detract considerably from 
pictures on which huge sums of money are spent. A good screen surface costs little, 
but its importance is beyond all comparison with its cost. This paper deals with the 
selection and use of screens for assuring good projected pictures. 

Picture presentation, especially since the advent of sound, is 
fraught with many difficulties, and the screen is by no means the least 
of these. The overcoming of all other difficulties the light source, 
the film, the lenses, etc. may all be for naught if the last one, the 
screen, should interfere. But the exhibitor often little realizes the 
importance of the screen. His projectionists take care of all other 
equipment, but even they allow a dirty or imperfect screen to pass 
without comment. This not only means a loss of efficiency, but 
a loss at the box-office as well, because of dissatisfied patrons. The 
objective of every exhibitor, therefore, should be to keep his screen 
in as good condition as possible at all times. 

When selecting a screen the following points, which will be dis- 
cussed individually, should be considered: 

(1) Adaptability to the particular theater; 

(2) Reflective efficiency; 

(3) Sound characteristics; 

(4) Durability; 

(5) Uniformity; 

(6) Fireproofing; 

(7) Illusion of depth; 

(8) Adaptability to color; 

(9) Size of screen required. 


There are many kinds of screens, but all come within three general 
classifications. There is no screen made today which is an average 
* Presented in the Symposium on Theater Practices at the Spring, 1931, 
Meeting at Hollywood, Calif. 

** Beaded Screen Corp., New York, N. Y. 


344 FRANCIS M. FALGE [j. S. M. P. E. 

type best suited to all houses. For that reason, screens should be 
selected which fit the characteristics of the particular house, bearing 
in mind the fact that theaters have very dissimilar characteristics. 
They may vary in width from 20 to 120 feet or more, and in length 
from 50 to 150 feet. They may have no balcony or they may have 
three; the angle of projection may be zero or it may be 35 degrees, 
and the screen may be from 10 to 30 feet from the front row of seats. 

Types of Screens 
There are three general types of screens: 

(a) Diffusive or matte 
(6) Reflective or metallic 
(c) Directive or beaded 

All three types of screens are made with openings to permit the 
passage of sound. 

Fortunately, screen characteristics are so definite that considera- 
tion of the vital principles of each of these types should permit a 
ready decision as to the screen best suited to a particular house. 

Practice seems to bear out the fact that a matte screen which 
radiates equally in all directions appears less brilliant the farther 
away the observer is from it. This may be due to the loss of light 
through the atmosphere, a smaller included angle of light, and the 
interference of light sources in the house. These factors in general 
tend to make the screen too brilliant for those in the front rows of 
seats, and not sufficiently brilliant for those in the rear seats. When 
selecting a screen, consideration should be given to these points. 

(a) The Diffusive Screen. Diffusive screens are made of cellulose 
coated materials; rubberized fabrics; closely woven treated ma- 
terials; coarsely woven materials with or without metallic fibers; 
woven materials with irregular glass particles; and coated metals. 
The distribution of light from a typical diffusive screen is shown in 
Fig. 1. The curve including the largest area, indicating the largest 
reflection values, is, in general, the best. 

The advantages of diffusive screens may be listed as follows: 

(1) They redirect a large percentage of light i. e., they are very efficient; 

(2) They are good for color picture projection*'. e. t they are. not color- 

selective ; 

(3) They redirect light through wide angles, giving satisfactory projection 

for wide theaters or for theaters with steep projection angles. 

Sept., 1931] 



(b) The Reflective Screen. Reflective screens are made of alu- 
minum and other polished and coated materials, and have varying 
degrees of diffusiveness. 

FIG. 1. Characteristics of diffusive screens. 

Their advantages may be listed as follows: 

(1) They build up the intensity of the reflected light so that under certain 

conditions they add to the apparent brilliancy as viewed from the 
rear seats; 

(2) Their use results in economies in projection in houses which have large 

ratios of length to breadth. 

The disadvantages of reflective screens are: 

(1) They are not desirable where the angles of projection are greater than 10 


(2) They can be used in relatively few houses ; 



[J. S. M. P. E. 

(3) They are not satisfactory for the projection of colored pictures i. e. t 
they are color-selective. 

We may conclude, therefore, that reflective screens are useful for 
few houses because of prevalent conditions and their limited re- 
flection angles. Also, they are not good for color picture projection. 
(c) The Directive Screen. Directive screens are diffusing screens 
on which are imbedded glass globules; they are also called "beaded 

\~\ \ 

FIG. 2. Characteristics of beaded screens. 

screens." The distribution of light from such a screen is shown in 
Fig. 2. 

Their advantages may be listed as follows: 

(1) They build up the intensity of the reflected light so that a more brilliant 
picture can be seen from the rear seats; 

Sept., 1931] 



(2) They redirect the light so that to spectators in the balcony the picture 

appears as good as to those on the main floor; 

(3) They redirect the light in such a manner as to result in decided econo- 


(4) They assist in the illusion of the third dimension ; 

(5) They can be satisfactorily maintained, and retain much of their original 


(6) They reduce the glare seen from seats near the screen; 

(7) Because of their apparent brightness, they add life and brilliancy to color 


The disadvantages of directive screens are: 

(1) They are not desirable for theaters having projection angles greater 

than 20 degrees because of their directive nature; 

(2) They are not desirable for wide houses. 

20 30 40 50 60 7O 80, 90 100 110 \ZQ 

FIG. 3. Showing relation between width of house and angle of projection. 

In conclusion it may be stated that beaded screens, while very 
efficient, redirect the light and provide a more satisfactory picture 
in houses of medium width having projection angles up to 20 de- 
grees. Because of the great brilliancy and the decided contrasts, 
the tone qualities of the picture are enhanced, especially in the case 
of color pictures. Beaded screens also redirect the light so as to 
provide those in the balcony with as good a picture as those on the 
main floor. 


[J. S. M. P.E. 

Selection of a Screen 

Invariably, it is a mistake to select a screen for one theater by 
viewing a screen in another theater. The many whims of projection 
equipment all contribute to mislead the observer, and in the final 
analysis, the characteristics of the houses will probably differ so 
much that a proper choice is impossible. Then, too, our eyes are 
not trained to evaluate the brightnesses in cases such as these. 

Consideration of the foregoing analysis, the charts of Fig. 3 and 
Fig. 4, and the physical characteristics of the particular theater for 











60 40 20 20 40 


FIG. 4. Brightness characteristics of various screens. 


which the screen is intended, will permit the selection of the best 
type. The other factors which follow will assist in making the 
proper selection of the best screen of that type. 


The total reflection of light from a screen, apart from measure- 
ments of its reflection characteristics in various directions, is very 
important, as it is on this factor that one phase of efficiency depends. 
Of two similar types of screen, the one with the highest over-all 


efficiency is likely to prove best. This is illustrated in Fig. 1, where 
the largest curve indicates the most efficient screen. The reflective 
efficiency of the screen is closely linked with the reflective efficiency 
of the coating material, titanium pigment being an excellent white 
reflective pigment. Aluminum, on the contrary, has relatively low 
efficiency, and consequently metallic screens are usually of low 
efficiency. Light tests of screens should include measurements of 
reflective efficiency. 


In practically all cases, horns are now placed behind the screen, 
the sound passing through the screen via interstices in woven cloth 
or perforations in opaque material. When this method was first 

to .!i.;si:*ai!!S?*v*jj?;*n*i* 


w w ^ w Ji*s?*"j?r5iKnJ*?*in* 

w ** 
^9| ^U ^fc . . *'<* J 

!* *****.. ..* 

$,.... t* **# V* - t * .< ** 
* <.**.< 
.#.. ** <-*. 

... *%-. 

Perforated Porous- Beaded 

FIG. 5. Screen openings for transmission of sound. 

used, the matter of sound transmission was considered all-important, 
compared with other considerations, and the picture suffered de- 
cidedly. It was later found that a relatively small percentage 
of open space as low as 4 per cent could be used, the present 
compromise being about 8 per cent. An arbitrary figure of ap- 
proximately 3 decibels loss was decided as allowable by Electrical 
Research Products, Inc. The RCA and other manufacturers have 
allowed somewhat greater tolerances. Considering the great losses 
in other parts of the system, such as in the horns, the allowable loss 
for screens would seem rather severe, but fortunately, a fairly good 
picture can be produced on a screen meeting this requirement. 
Also, because of varying methods of test, it does not seem possible 
to make two tests that check, so that, under the present system, 
the value of these tests is questionable. 

Fig. 5 is given as a matter of interest, showing the openings in a 
porous and a perforated screen, magnified 100 times. 

350 FRANCIS M. FALGE [j. s. M. P. E. 


Under this subject the following factors must be considered: 

(a) The ability of the screen to withstand abuse, during handling and 

(6) Its strength at the seams; 

(c) The effect of dirt collection; 

(d) The effect of washing and reprocessing. 

The abuse that the average sound screen receives is astonishing. 
When hanging the screen, often too little care is taken, and there is 
always the possibility of tearing or damaging the surface. Ac- 
companying all new screens are carefully written instructions which 
are very valuable to the exhibitor in regard to saving time and 
obtaining the proper service from his screen. Ruggedness of material 
is a factor to consider in selecting a screen, but any screen is likely 
to suffer because of abuse. Furthermore, ruggedness seems to play 
no part in its life, as other factors, such as the collecting of dirt and 
method of maintaining the screen, are more important. The seams 
should be as strong as possible, but no seams will withstand con- 
siderable abuse. 

The accumulation of dirt, the washing of the screen, and methods 
of reprocessing it are the factors which determine the life of a sound 
screen. If properly maintained, screens may have an effective 
life of one and one-half to two years. The average effective life of a 
sound screen is one year; screens kept in service longer than this 
handicap the exhibitor to a considerable extent unless they are 
properly and regularly serviced. 


Two factors must be considered under this heading: (a) the uni- 
formity when new, and (b) the uniformity after being used a while 
and after cleaning or reprocessing. 

The slightest imperfection in weave or variations in depth of 
coating may result in a non-uniform surface; this may happen even 
when the greatest of care is taken. Panels must therefore be carefully 
matched and inspected to see that they are of the same color and are 
free from imperfections. 

The processing must be so uniform and exact that surface con- 
ditions and time will not cause a lack of uniformity. All screens 
in use today become yellow with age to a certain extent. If the 
yellowing is uniform, it is not likely to be objectionable. Improper 

Sept., r l93i] MOTION PICTURE SCREENS 351 

cleaning or reprocessing may introduce streaks and imperfections, 
and may considerably increase the tendency to become yellow. 
At the time of processing, the screens may have a uniform appearance, 
but when dry the imperfections will gradually appear. Be sure that 
this is given consideration before allowing a screen to be resurfaced. 


Some time ago, because screens were made of highly inflammable 
cellulose materials, considerable agitation was raised in certain 
quarters concerning fireproof screens. By adding certain ingre- 
dients and eliminating others, the various screen coatings were 
made fire-resistant. Fabrics are best made fireproof by impregnating 
them. A slow-burning material, however, when stretched verti- 
cally, does not constitute a fire hazard ; but if a fire-resistant material 
is selected, there need be no fear of objection by local inspectors. 

Successful fireproofing of a screen immediately after it is made 
or while in place in the theater has not yet been accomplished. 
Screens are such a small item of the stage equipment, and so much 
less inflammable, that there need be no fear of fire from them. In 
general, it is best for each exhibitor to choose his screen according 
to his local ordinances. 


The illusion of depth is a very debatable matter; it seems to be 
connected with the method of photography used. By obtaining 
the proper contrast between highlights and shadows, an illusion of 
depth seems to be created. Beaded screens have been selected for 
wide film projection in a number of instances because of this feature. 


Color brilliance and purity is, to a considerable extent, dependent 
on the light intensity. For this reason a bright screen will, in general, 
if of neutral character, give better results for all colors than a screen 
which is less bright. For colors, screens should have no tint other 
than that which is required to neutralize the color of the light source, 
assuming that it has a definite color. A metallic screen is usually 
quite color-selective, whereas beaded and white diffusive screens 
are neutral in character. Closely paralleling this problem is that 
of obtaining the correct tone quality of the reflected picture. At- 
tempts to tint the screens in order to impart a certain tone quality 
to the picture are likely to be undesirable when colored pictures are 

FRANCIS M. FALGE [j. s. M. P. E. 

projected, and because of the different qualities of the various arc 
sources themselves. 


The problem of choosing the proper size of screen is an important 
one. A new installation is the simplest to plan, but when a theater 
needs a new screen, the problem should be carefully considered. 
The problem is of sufficient importance to warrant the replacing 
of the objective lens if a different size of screen seems desirable. 

Standard Sizes. A system of standard screen sizes is highly de- 
sirable, and will result in economies and other advantages for both the 
exhibitor and the manufacturer. Less wastage results, errors in 
ordering are made less frequently, shipping is expedited, cleaning is 
facilitated, and costs and prices are consequently reduced. The 
Projection Screens Committee of the Society of Motion Picture 
Engineers is now developing recommendations for standard sizes. 
Information based on standards adopted individually by large 
circuits and manufacturers gives the following list of sizes: 

Description Picture Screen Inside of Frame 

Standard 9'0 by 12' 9'6 by 12'6 10'6 by 13'6 



" 14' 

ll'O ' 


12'0 " 




. " 16' 

12'6 " 


13 '6 " 



13 '6 

" 18' 

14 '0 " 


15'0 " 

19 '6 



" 20' 

15'6 " 


16'6 " 

21 '6 



" 22' 

17'0 " 


18'0 " 

23 '6 



" 24' 

18'6 " 


19'6 " 




" 36' 

25'0 " 


26'0 " 




" 40' 

27'0 " 

41 '0 

28'0 " 

42 '0 



" 40' 

29'0 " 

41 '0 

30'0 " 


Wherever possible a standard size should be substituted for a non- 
standard. When ordering screens, the three dimensions should be 
given ; prices are based on picture sizes. 


Theaters are planned with definite lines of sight, and care must 
be taken to keep the screen in the line of vision, especially when 
using a screen modifier. Older theaters generally used a line of sight 
which provided a clear view of 16 feet from the stage floor at a point 
4 feet back of the curtain line, which therefore often limited the size 
of the screen to 15 by 20 feet. Newer theaters often allow for a 

Sept., l93lj 



considerably greater height. The accompanying diagram (Fig. 6) 
illustrates these limitations. 

The distance from the front row of seats to the screen is one of the 
determining factors for the size of the screen. The larger the picture, 
the worse will the imperfections, such as graininess in the film, appear. 

FIG. 6. Factors limiting the size of screen (typical motion picture theater). 


TO 80 90 100 110 120 130 140 ISO 160 







J L 

J L 

J I t L 

V 6 8 10 12 ,14 16 Ifl 20 22 24 26 28 3O 32 34 36 38 


FIG. 7. Curves for determining proper size of picture. 

354 FRANCIS M. FALGE [j. s. M. P. E. 

These imperfections are very noticeable and objectionable to spec- 
tators sitting close to the screen. The eye can satisfactorily ac- 
commodate itself over an angle hardly more than 45 degrees, so that 
the distance of the front row from the screen should be approximately 

15 inches for each foot of screen width. For a 15-foot picture, 
a distance of at least 18 ! /2 feet should therefore be provided. 

The size of the picture should also be determined by its distance 
from the rear seats. The width of the screen should be approxi- 
mately Ye the distance from the screen to the rear seats. For a 
distance of 120 feet, therefore, a 20-foot picture should be provided. 
Fig. 7 shows curves which may be used in determining the proper 
size of the picture. 


The intensity of the lamps, the perfection of the optical system, 
and the length of throw should also aid in determining the size 
of the picture. Here, however, the character of the screen must be 
considered. If it is of the beaded type, in a house adapted to it, a 
considerably larger picture can be used because of the increased 
brightness of the picture as seen from most seats. 

It is a fact that the smaller the screen, under a given set of con- 
ditions, the brighter it appears. For this reason there is a definite 
maximum limit to the size of the picture when using Mazda or low- 
intensity arc lamps of 18 to 28 amperes. Practical tests have de- 
termined these sizes to be as follows: 

Light Source 






100 ft. 

12 X 16 



100 " 

15 " 20 

Low Intensity 


125 " 

15 " 20 

Low Intensity 


175 " 

12 " 16 



125 " 

18 " 24 


175 " 

18 " 24 

This table is based on the best figures available at this time re- 
garding screen illumination, which varies from 3 to 7 foot-candles 
with the shutter in operation, for a picture of average size. For 
Hi-low and high-intensity light sources, there seem to be no limi- 
tations beyond the reasonable ones already placed. 

It should be remembered that when a given light source at a given 
distance is used to project on a larger screen, the screen brightness 
will be lessened, just as a 25-watt lamp in a small room will light a 


theater auditorium much less brightly A 12 by 16-foot screen 
having an area of 192 square feet is almost twice as bright as a 15 
by 20-foot screen having an area of 300 square feet, under the same 
conditions. Therefore, if a screen is not already more than bright 
enough, a change to a larger screen should not be considered unless it 
is to be changed to the beaded type. 


Practical showmanship is responsible at times for causing ex- 
hibitors to do things that may not be technically correct. The excite- 
ment about large pictures (which was accomplished practically, but 
not satisfactorily, by merely changing the sizes of screen and picture) 
caused the exhibitors to feel that it is necessary to have a larger 
screen than is ordinarily desirable. The maximum size of picture, 
except in unusual cases, should be 18 by 24 feet. If a screen modifier 
is to be used, there must be sufficient difference between the sizes 
of the small and large pictures to make the effect worth while. A 
change from a 20 by 26-foot picture to a 24 by 36-foot picture would 
not be desirable; however, a change from a 15 by 20-foot standard 
picture would provide the desired effect. 


Local conditions determine to a great extent the location of the 
screen. In general, it may be said that the illusion of realism is 
best maintained by placing the screen either as close to the floor as 
possible or not more than 18 inches above it. 

When possible, the floor of the stage on the house side of the screen 
should be covered or painted with a dark non-reflecting, non-glossy ma- 
terial, as the stage floor produces annoying reflections of the picture. 

The screen should, of course, have a mask around it to properly 
frame the picture, and to reduce the "jumping" effect which occurs 
when poor film or poor equipment is used. This mask is usually a black 
cloth free from gloss, but at various times a less absorptive material 
has been advocated to reduce the sharp contrast between the frame 
and the picture. Because of jumping, it is not desirable to use a light 
material next to the screen; the desired effect may be accomplished 
by a graded surface, with the darkest material adjacent the screen. 


Sometimes screens are tilted in order to correct for keystoning, 
or, with silver screens, to redirect the light to better advantage. 
This is a difficult problem, and furthermore, it might be stated that a 

356 FRANCIS M. FALGE [j. S. M. P. E. 

tilted screen collects more dirt than an upright screen. Tilting 
should be restricted to silver screens. 

Key stoning and side-view distortion are due to large projection 
angles or poor perspective, and cannot be corrected by using a modi- 
fied aperture plate. Side-view distortion cannot be corrected, 
but can be avoided to a certain extent by keeping the screen as far 
from the front seats as possible, and by eliminating the wide front 


The principles of correct lighting for theaters are so well known 
that only a few of them will be mentioned here: 

(a) The intensity of illumination should gradually diminish from the street to 
the auditorium, so that the eyes may gradually become accommodated to the low 

(6) Auditorium lighting should be of low intensity. The auditorium should 
be only sufficiently bright to permit patrons to readily locate empty seats, and 
not so bright that they will be distracted by movements of other people. Less 
light is needed in the front of the auditorium. 

(c) All light sources should be diffused so that no points of considerable 
brightness are apparent, and no lights should be near the line of vision when 
viewing the picture. 

(d) The light should be so deflected that as little as possible falls on the screen. 


The manner of installing screens has an important bearing on the 
results obtained with them and the economies effected. A few rules 
for installing screens will therefore be given. However, when 
manufacturers' instructions are available, they should be followed 
to the letter. 

(1) Whenever possible, and wherever a screen is smaller than 15 
by 20 feet, the screen can best be installed by assembling the frame 
on the stage or on the seats (Fig. 8), with the top toward the place 
the screen is to be. 

(a) Lace the left side, which is the top screen surface, on the roll. 
Follow with the top and bottom of the screen, and then the right- 
hand side. 

(b) When the screen is in place, tighten the laces ; in the case of a 
beaded screen, where there is no need for extreme tightness, do not 
stretch other than to remove the wrinkles. 

(2) If the frame is already in an upright position, a line 
should be fastened to the shipping roller and the screen should be 

Sept., 1931] 



raised into place on the left side of the frame, rested on the bottom 
rail, and fastened by the line to the top rail. Care should be taken 
not to crush the screen or allow the material to sag from the roller. 

(a) With small pieces of line, starting at the corner grommet, 
tie the screen into place at the top grommet, unrolling the screen as 
each grommet is tied to the frame. 

FIG. 8. (A) Unrolling the screen on the frame; (B) the screen 
partly unrolled. 

(b) Lace the top of the screen after it is temporarily in position; 
then lace the bottom, and finally the sides. 

.(c) . . When the lacing is finished, tighten it gradually, to free it of 
excess wrinkles. Do not stretch tightly. 


There are four phases to the maintenance of screens.; _ one pertains 
to the preventing of dirt from accumulating on .the -screen ; another 
to freeing it of excess dirt; the third to a comptete and thorough 

358 FRANCIS M. FALGE [j. s. M. P. E. 

cleaning of the screen ; and the fourth to the renewing of the surface. 
The final objective is to keep the screen surface as nearly perfect 
as possible at all times by taking all precautions and by systemati- 
cally attending to it. 


The surfaces of sound screens have very dissimilar characteristics. 
Some are very rough, some smooth, some hard, and some are sticky. 
The perforations add much to their ability to collect dirt, and porosity 
of the surface adds to a somewhat lesser degree. The circulation 
of air through the openings also makes it easier for the screen to 
collect dirt. Silver screens collect dirt, just as do the beaded and 
white screens; furthermore, they become tarnished, resulting in a 
lowered reflection value. A hard white screen is better than a sticky 
one from the maintenance standpoint. 


The amount of dirt deposited on the surfaces of the screen de- 
pends on the atmosphere of the house, on the neighborhood, on the 
circulation of air in the theater, and on the precautions taken to 
protect the screen. The first step to be taken toward keeping the 
surface clean is to determine whence the dirt comes, and to alleviate 
the difficulty at its source. The following are the more obvious 
sources of dirt ; and remedies: 

(1) Dirt falling from overhead and draperies. Thoroughly 
clean overhead, side draperies, and masking. Prevent travelers from 
brushing the screen. 

(2) Stirring up of dirt by cleaners. Cover the screen at night 
when not in use, even though with only the cheapest kind of material. 

(3) Circulation of air through the screen. Close doors, etc., 
which cause drafts, and back the screen, close to the horns, with a 
neutral gray material to prevent air from circulating through the 


Even after taking all these precautions, the screen will collect 
dirt. Inspection will indicate whether the dirt is dry or greasy and, 
therefore, whether the screen can be brushed. If the dirt is dry, 
the screen should be brushed with a long-handled special screen 
brush. It is also well to vacuum-clean the back of the screen once a 
week. The brush should be kept clean. 



No satisfactory method of cleaning screens has been suggested 
as yet. It is possible to clean small samples of screen material, but 
the cleaning of screens installed in the theater or when returned 
to the factory is not practicable. The screen sags, and water soaks 
in at the perforations, causing deterioration of the surface. Streaks 
result from unequal drying. The soap causes the screen to become 
yellow after a few days. If screens must be cleaned, however, there 
are certain instructions which, if followed, will produce better results 
than are usually obtained: 

(1) Great care must be taken ; 

(2) Use two buckets, one for the cleaning solution and the other for clean 


(3) Keep the water and solution clean at all times; 

(4) Free the surroundings and screen of excess dirt before cleaning; vacuum 


(5) Use soft sponges and keep them dry, so that no water will run down the 

screen ; 

(6) Work from the bottom to the top of the screen; 

(7) Use plenty of light. 


Replacing the surface of diffusing screens by spraying is receiving 
considerable attention. When carefully done, and when the proper 
material is used, a satisfactory job may be possible. The material 
should have a high reflection value, and should become yellow as 
little as possible. Here again, the screen and its surroundings should 
first be cleaned thoroughly. 

In conclusion, in order to properly select, purchase, install, and 
maintain a screen, the following outline should be carefully followed: 

(1) Decide on the proper type of screen for the house. 

(a) If the projection angle is less than 20 degrees and the house is not 

extremely wide, use a beaded screen. 
(6) If the projection angle is greater than 20 degrees or the house is 

extremely wide, use a matte screen. 

(2) Choose the best screen surface of this type. 

(3) Analyze the house conditions and select the proper size of screen. 

(4) Install the screen properly, following the manufacturer's instructions. 

(5) Permit no circulation of air through the screen. 

(6) Cover the screen when not in use. 

(7) Brush the screen regularly once a week, with the proper kind of brush. 

360 FRANCIS M. FALGE [j. s. M. P. E. 


PRESIDENT CRABTREE: How are the screens cleaned? If the brush method is 
used, how are they brushed ? Is the screen taken down from its position or is it 
brushed in place? Also, how is the screen resurfaced? What is the cost of re- 
surfacing in comparison with the cost of the screen? Is it worth while? 

MR. FALGE: The screen is cleaned in position with a very soft, long-handled 
brush. Cleaning is very simple, but is often neglected. Some one in every 
theater should be given the responsibility of keeping the screen clean. The cost 
of taking down the screen, packing and shipping it to be resurfaced, and mounting 
again is so great that it is better to clean the screen in position. Screens may be 
resurfaced in a number of ways, the spray process being the most satisfactory. 
The cost of this treatment varies in different places, from 10 to 20 cents per foot. 
A new screen may cost from 2 'A to 4 times the cost of resurfacing, depending 
upon the amount of surface to be treated. Screens can be resurfaced satis- 
factorily, but in general, the process is not satisfactory, as the material used for 
resurfacing becomes yellow and is not always put on uniformly. 

PRESIDENT CRABTREE: What is the effect of spraying a beaded screen? 
Is it cleaned by spraying, or were you referring to diffuse screens? 

MR. FALGE: I was referring to diffuse screens. No good is accomplished by 
spraying a beaded screen, as the spraying causes the beads to lose their directive 
qualities. In general, it is extremely difficult to properly clean screens on ac- 
count of the wide expanse of the flat surfaces. Beaded screens can be cleaned 
satisfactorily, but the process is very complicated. 

PRESIDENT CRABTREE: Could some solvent be used for cleaning the beaded 


MR. FALGE: To a certain extent; but the solvents that have been tried 
have loosened the adhesion of the beads and so such methods have not been 
found satisfactory up to the present. 

PRESIDENT CRABTREE: The matter of standardizing screen sizes is very im- 
portant. Has this matter been brought to the attention of the Projection Screens 

MR. FALGE: Yes, but nothing definite has been done about it as yet. 

MR. SCHLANGER: The information given in this paper referring to the proper 
distance between the seats and the screen is very important and should be re- 
ferred to the American Institute of Architects. In relation to the shape of the 
screen, I suggest that perhaps Mr. Dieterich might say something about the restful 
physiological effect of the 3 to 5 ratio on the human eye. 

MR. DIETERICH: Yesterday I briefly mentioned the fact that there is a mini- 
mum distance required between the eyes and the screen for comfortably viewing 
the picture. To go a little deeper into the discussion we must consider the 
sight characteristics of the eyes, which when plotted, assume a peculiar egg-shaped 
form for each eye. The combination of the two characteristics produces a more or 
less heart-shaped curve for the combined characteristics of the two eyes i.e., 
for binocular vision. If we inscribe a rectangle into the combined characteristic 
we are led to the classical ratio of height to width of 1 to 1.6. As long as we 
have to change the proportions of the visible picture which we must do sooner 
or later we should consider the esthetic demands, because they control to 
a great extent the reaction of the public, which again influences box-office re- 


turns. As long as it is necessary to change the dimensions, I am endeavoring to 
advocate that we should change in accordance with this ratio. There will be 
a number of technical difficulties, and problems to overcome, but they will have 
to be overcome sooner or later, in any event. The Standards Committee has 
suggested a 50-mm. width for production reasons, but we can just as well use the 
proper proportions for this width as for any other. Mr. Schlanger suggested 
that when one sits in front of a screen that is 40 feet wide, he may come closer 
than 40 feet. However, this would not place the screen within the "easy" range 
of the eye. The eye must exert an effort to encompass an angle greater than 
60 degrees and although our total vision is limited only by about 180 degrees, 
it becomes a painful effort to use it to its full extent. Along the horizontal 
axis of vision, the "easy" range is normally 30 degrees on each side, and along 
the vertical axis about 10 degrees above and 20 degrees below the horizontal. 
If the scheme of Mr. Schlanger is in accordance with these physiological facts, 
he will find that the spectator will enjoy the picture more than in the past. As 
to the question of depth perception, the recognition of depth in the wide picture 
is due to the fact that when one looks at a wide screen, the distances to the edges 
of the picture are perceptibly greater than the distance to the center, and the eye 
has to accommodate itself to such different focal values. Therefore, the only 
means of perception, which is by the final nerve center, would cause a reaction, 
resulting in a muscular effort to accommodate the eye. Therefore, the wide 
picture has certain disagreeable effects for the present front seats, but which 
lessen as the distance from the screen increases. The minimum distance between 
the screen and the front seats, should not be less than the width of the 

MR. FALGE : The ratio you suggested is close to the 3 to 5 ratio which I men- 
tioned previously. 

MR. JONES: There was one statement in Mr. Paige's paper I should like to 
question. In discussing the diffusing type of screen he stated that the brilliance 
of the screen depends upon the viewing distance. I cannot see why the argument 
applies to the diffuse type of screen and not to the beaded type. It is quite 
possible that the brilliance of the screen -that is, the apparent brightness is to a 
certain extent influenced by the angle of the screen and by the surroundings. I 
think it is quite possible and I know it is true that whether the screen appears 
to be more brilliant at one distance than at another will depend upon the sur- 
roundings of the screen. I think we should recognize that that characteristic, 
which may be a true phenomenon, is a characteristic of all types of screens, and I 
cannot see that it is a characteristic of a diffuse type of screen any more than of any 

MR. FALGE: What I meant to convey was that this effect is more pronounced 
in the case of the beaded screen. I referred to it briefly in connection with the 
beaded screen. As far as the surroundings are concerned, if too much light is 
present, the pupils of the eyes become smaller and the screen does not appear as 
brilliant as one would like it to be. 

MR. OTIS: Have any measurements been made on the diffusiveness of the 
screens to color? 

MR. FALGE: Do you refer to a particular one of the three types, or to all 
screens? I do not believe that such measurements have been made. 


MR. SCHLANGER: Referring to the shape of the picture and the desirability of 
retaining the 3 to 5 ratio, it is possible to change the shape of the screen through- 
out a picture so as to present different geometrical forms triangular, rectangular, 
circular, etc. I understand that some work has already been done along that 

MR. DIETERICH: Madame Ducat, the only female member of the Legion of 
Honor, has invented a new "panel" aperture. Her idea is that everyone who 
has a sense of the artistic frames a picture or composition according to the com- 
position, and does not take the frame and fill it with the composition. The frame 
should be under the control of the cameraman so that he may instantaneously 
alter the picture frame as desired. This does not depart from the 1 to 1.6 ratio 
for the shape because this ratio is an esthetically fundamental one from which 
any number of frame sizes can be developed. Her idea of changing the frame size 
according to the action has been successfully used because she understands the 
correct use of the panel frame. 


Summary. An innovation at the Spring, 1931, Meeting of the Society at Holly- 
wood, Calif., was an exhibition of new apparatus held in the annex of the American 
Legion Auditorium. The exhibit aroused such great interest that it is hoped to hold 
similar exhibits at future conventions. 

Exhibitors were required to conform to the following regulations: (a) It was neces- 
sary that the apparatus be new or have been developed or improved within the previous 
tweke months; (&) No pamphlets or advertising literature were permitted; (c) Each 
exhibitor was permitted to display a small card giving the name of the manufacturing 
concern and each piece of equipment was labeled with a plain label free of the name 
of the manufacturer; (d) A technical expert capable of describing the features of the 
apparatus exhibited was required to be present during the period of the exhibition. 


This recording system was primarily designed for industrial, news, 
and travel work. It employs two direct current motors operating in 
synchronism, and enables the cameraman to use any motion picture 
camera in synchronism with the recorder and produce a separate 
sound track on positive film. The camera motor hangs under the 
camera by two straps which are snapped on and off quickly, and 
operates the camera through a flexible shaft which can be plugged 
into the regular Bell & Howell or Mitchell cameras. The motors 
operate on 10 volt d-c. and are electrically interlocked for syn- 
chronism (Fig. 2). 

Fig. 3. shows the recording head. A tachometer, footage counter 
and a 1,000 ft. Mitchell magazine are included. The motor mounted 
on the base is one of the d-c. interlocking motors. One switch con- 
trols the recorder, another switch the camera motor, and a third is 
the interlocking switch which throws the camera and motor into 
synchronism. The recording lamp holder is removable for cleaning 
and threading. When replaced it slips on a pilot pin with a stop 
screw so that it will always be in proper register. A mechanical filter 
is included between the motor and the recording head. 

The amplifier consists of 4 resistance-coupled stages, provision 
being made for accomodating two microphones. A lamp voltage 
regulator, plate current meter, and volume indicator are also included 

* Audio- Camex System of the Hollywood Camera Exchange, Hollywood, Calif. 




[J. S. M. P. E. 

Sept., 1931] 



with the amplifier. The recording glow lamp used is known as the 
Audio-Lite and is said to have a life equivalent to the recording time 
of 30,000 to 100,000 feet, of film. Its impedance is about 7,000 ohms, 
and it is constructed of non-volatile electrodes. 

The amplifiers, motors, recording head accessories, etc., are all con- 
tained in seven metal cases. 

All the connectors are arranged differently ; the microphone connect- 
ors are 5 point connectors, the battery cable connectors 6 point, and 
the Audio-Lite connectors 4 point, etc., thus making it impossible to 
connect the apparatus incorrectly. 
The bullet type microphone is a two 
stage microphone and is used as a 
condenser transmitter. It is mounted 
on the swivel head and has a cannon 
connector. The microphone stand is 


The Moreno-Snyder continuous 
camera employs an optical system in 
which the image is moved in syn- 
chronism with the film by means of a 
single moving part which intercepts 
the light. The light passes directly 
from the objective to the film through 
the optical system without being 
handled by reflectors or similar ele- 
ments. A means is provided for con- 
trolling the framing of the picture on 
the film in addition to a light control 
for governing the exposure. The film 
moves continuously, and the film feeding mechanism is synchronized 
with the moving element of the optical system. Included with the 
camera is an exposure meter employing a photoelectric cell which 
permits matching of the exposure for a given scene with that of any 
scene photographed previously. For the standard film speed of 90 feet 
per minute, the exposure time per picture frame is x /24 of a second. 
The lens turret provides for three lenses (Fig. 4) and the focusing posi- 
tion and the exposure position of either lens or camera are the same. 

FIG. 2. Audio-Camex portable 
recording system attached to a 

* Moreno-Snyder Camera Corp., Hollywood, Calif. 



FIG. 3. Recording head of Audio-Camex portable recording system. 

FIG. 4. Moreno-Snyder non-intermittent 
camera front view. 

Sept., 1931] 



By exerting a slight pressure on a small piston a prism is made to 
intercept the rays of light and direct them to the eye through a focus- 
ing finder (Fig. 5). This prism withdraws automatically after the 
third frame of film is past the aperture. The camera is silent and 
requires no blimp or muffler. Due to the continuous motion of the 
film, buckling is eliminated. Delivery and wind-up film magazines are 
detachable and interchangeable, while the camera can be operated as a 

FIG. 5. Left side view, Moreno-Snyder camera showing focusing device. 

speed camera for slow motion photography, and will run at 300 frames 
per second, or 125 ft. of film per minute, without change or adjustment. 
The optical system includes a matte or exposure aperture, an ob- 
jective lens, a moving lens unit, a corrective lens, and an exposure 
control, arranged on the camera in the order named. The moving 
lens unit moves the image-bearing shafts of light in synchronism with 
the film. It intercepts the light beam passing from the objective to 



[j. S. M. P. E. 

the film at one point only in the optical system, and moves it across 
the axis of the optical system constantly, and in a direction opposite 
to that in which the film is moved. The moving lens unit moves 
across the axis of the optical system at a point behind the objective 
lens, i. e., at a point located between the objective lens and the film. 
The moving lens element is annular in general configuration and is 
rotatively mounted, so that it intercepts the axis of the optical system 
at the desired point, while the portion of the film that is exposed is 

FIG. 6. Interior of Moreno-Snyder non-intermittent camera. 

within the moving lens unit. In general the inner face of the moving 
lens unit is curved concentric with the axis of rotation of the unit, 
while its outer face is polygonal (Fig. 6). 

A corrective lens is located immediately behind the moving lens 
unit between the latter and the film. The exposure control is located 
immediately in front of the film and includes a pair of shutter plates 
normally spaced apart to admit light to the film and adjustable in 
opposite directions parallel with the axis of movement of the film to 

Sept., 1931] 



widen or narrow the opening through which light is admitted. Fig. 7 
shows various details on the rear of the Moreno-Snyder continuous 


This camera was designed particularly for quiet operation. The 
movement is entirely new, and no cams are used. The motion of 
the film is accomplished by eccentrics pivoted with levers, and the 

FIG. 7. Moreno-Snyder non-inter- 
mittent camera rear view showing 
exposure meter and "Thermo-Head." 

film travel is approximately the same as in the standard Mitchell 
camera. The pilot pins have a longer "dwell" or stationary period 
during exposure. Sawing of the film head is present but has been 
considerably reduced. A pair of gears from shutter shaft to move- 
ment and the worm of the shutter shaft drive the sprocket through a 
worm wheel. Another pair of gears is necessary in the motor mount- 
ing to change the speed to 1,440 rpm. By this means the number of 

* Mitchell Camera Corp., Hollywood, Calif. 



[J. S. M. p. E. 

gears required is made as small as possible. The gears and worm 
wheel are enclosed in an oil-proof housing, while the magazine is made 
slightly larger to allow room for sound proofing material and more 
silent bearings. An adjuster plate is provided between the camera and 
the magazine which insulates the magazine from the camera with 
sound-absorbing material. An adjuster shutter is incorporated but 
the dissolve mechanism has been eliminated. The face of the camera 
is of new design, having one lens mount focused from the rear of the 

FIG. 8. Silent Mitchell camera for studio work. 

camera and a scale plate in the face indicates the setting of the lens. 
The motor is integral with the camera door. The one shown in Fig. 8 
is to be changed, and will be enclosed in a case containing sound- 
absorbing material. 


This 35-mm. fully automatic sound and picture printer prints both 
sound and picture at a single operation (Fig. 9) . Notches on the edge 

* Bell & Howell Co., Chicago, 111. 

Sept., 1931] 



of the film and similar devices generally likely to get out of order are 
eliminated. Interlocking of operating levers makes it impossible to 
operate the machine incorrectly and means for stopping the machine 
automatically have been provided in case the film breaks, a lamp 
burns out, etc. After being set up, the machine only needs to be 

FIG. 9. 

Bell & Howell 35-mm. automatic sound and picture production 

threaded with fresh positive stock at the completion of the printing of 
each reel. It runs equally well in either direction. One handle starts 
the machine either forward or backward, and controls the motor, 
brake, lights, air, vacuum tension, weights, trip locks between gates, 
etc. It is impossible to start the machine if any gate is open or if 


any lamp is burned out. A traveling matte is used between the print- 
ing light and the negative film to control the printing value of the 
light without using notches on the film or similar devices. The travel- 
ing matte runs at one-fourth the speed of the negative, the purpose of 
the matte film being to secure control of the densitometric value 
of the final print. Densitometric control of printing light values is 
sufficiently exact to permit the same negative and traveling matte to 
be used in any printer, irrespective of location, with assurance of exact 

FIG. 10. Tanar portable sound recording equipment. 

duplication of print densities. One operator can take care of several 
printers and each man should be able to handle six to twenty-five 
printers, depending on the nature of the work and the number of 
set-ups required. 


The complete Tanar portable sound equipment used in the single 
system is shown in Fig. 10. It is carried in two moisture-proof cases 
weighing 60 pounds each. The upright case contains the amplifier 

* Tanar Corp., Ltd., Hollywood, Calif. 

Sept., 1931] 



tube batteries for the amplifier and three batteries for supplying cur- 
rent to drive the camera motor. The flat case contains the "B" and 
"Tanar-Light" batteries, head phones, camera motor, two Tanar- 
Lights, and a microphone. A compartment in the lid of this case carries 
three cables for batteries, microphones, and camera connections. In 
the complete equipment a case is supplied for housing the camera. 
On the amplifier panel is included a volume indicator meter. The 
motor drive is very compact, light in weight, and is shown attached 
to the camera in Fig. 10. The drive operates on three "B" batteries. 

FIG. 11. Photoelectric cell monitoring device. 

The tachometer is carried directly to the main shaft, and the drive 
to the camera is completed through Celeron silent gears. A switch to 
start and stop the motor independent of the control panel and the 
variable speed knob are mounted on the motor assembly. The motor 
plugs directly into a Bell & Howell camera or a Mitchell camera with a 
suitable adaptor. A short length of cable with a Tanar socket on the 
end completes the connection to the Tanar-Light. The Tanar-Light 
is a glow tube with electrodes of tantalum. The variable density 
system of recording is used. 




[J. S. M. P. E. 

Metro-Goldwyn-Mayer Studios of Culver City, Calif., exhib- 
ited several light valves, a photoelectric cell monitoring device, and a 
photograph of a new valve stroboscope. The last-named device was 
in use at the studio at the time and could not be exhibited. The light 
valves are described in Mr. O. O. Ceccarini's paper entitled "Recent 
Contributions to Light- Valve Technic," published in this issue of the 
JOURNAL. They have a single grease-damped ribbon as compared 
with the standard valve, which has double ribbons with no dampling. 

The photoelectric cell monitoring device was designed to divert 

FIG. 12. Stroboscope for viewing light valves in operation. 

part of the light between the light valve and the recording objective 
into an efficient photoelectric cell, thereby eliminating part of the 
photoelectric cell amplifier and assuring quiet uniform PEC monitoring 
(Fig. 11). 

The light-valve stroboscope is a projection microscope with a 
stroboscope wheel in the beam of light, which permits examination of 
the light valve in operation. This machine is used in the routine 
adjustment and maintenance of light valves (Fig. 12). 

* Metro-Goldwyn-Mayer Studios, Culver City, Calif. 

Sept., 1931] 




This lens turret is adapted for use on either the standard Simplex 
or the Super-Simplex projection mechanism. The use of this turret 
makes it possible to change to any one of three lenses without having 
to remove them from the projector. This makes it particularly 
adaptable where different lenses are used on sound-on-film, silent, or 
sound-on-disk prints, magnascope, or other special lens effects 
(Fig. 13). 

The turret carries three lenses in individual lens mounts, and has 
both tilt and pan, as well as straight, vertical, and lateral adjustment. 

FIG. 13. A. B. C. projection lens turret front 

Each lens may be independently focused by a micrometer focusing 
screw. By means of adapters, the lens mounts accommodate all 
makes and focal lengths of lenses. 

Any one of the three lenses may be swung instantly into position 
and rigidly locked by means of a hardened steel taper locking pin. 
The turret proper is mounted in a double race ball-bearing mount, 
and provision is made for adjustment to compensate for wear. The 
turret can be easily attached to the projector without changing the 

* A. B. C. Products, Culver City, Calif. 



[J. S. M. P. E. 

original mechanism in any way. It is merely necessary to remove the 
front plate from the projector mechanism, and remove the old lens 
mount. Since the turret mechanism is self-contained and mounted 
on a new front plate it fits easily into place. The new door is so 

FIG. 14. A. B. C. projection lens turret rear view. 

designed and hinged that it will clear any light shield douser or other 
mechanism which the original Simplex door will clear (Fig. 14). 


Of late there has been a trend toward the larger picture in the 
theater. This has made it necessary to increase the light intensity in 

* Fox West Coast Service Corp., Los Angeles, Calif. 

Sept., 1931] 



order to illuminate the larger screen area properly. The resultant in- 
crease in light intensity at the source and at its concentration at the 
film aperture often causes sufficient heating of the film to make it 
warp and buckle, and get out of focus. 

A device for relieving this situation, which readily lends itself to 
attachment to the Powers mechanism, is fastened to the head mecha- 
nism at three triangular points, making a rigid assembly which can 
readily be installed by any competent projectionist without extensive 

FIG. 15. Rear shutter attachment for a projector. 

alterations to the mechanism (Fig. 15). The shutter adjusting device 
has two parts a screw bearing and a locking nut. When the adjust- 
ment is made, this nut locks the assembly in position. The old 
Powers shutter assembly is discarded. The shutter housing is of cast 
aluminum alloy and the shutter blades are equipped with vanes 
which create a rapid circulation of air. The shutter shaft bearings 
are phosphor bronze bushings which are easily replaceable. 

The standard set by other manufacturers in regard to the distance 
between the shutter plane and the film plane has been followed, per- 


milling any of Ihe modern lypes of lighl sources lo be used. The 
shuller diameler has been increased lo lake care of any wide angle 
lighl beam. 

Wilh Ihis lype of shuller il has been found necessary lo discard Ihe 
old slyle framing lever. In ils place has been subsliluled a rack and 
pinion melhod of changing Ihe posilion of Ihe framing carriage, Ihe 
laller being operaled by a shafl which exlends Ihrough Ihe head 
mechanism, wilh a suilable knob convenienlly localed on each side 
of Ihe projector head. The shuller shafl has been extended beyond 
Ihe frame in fronl lo allow for Ihe use of cue-melers, speed indica- 
tes, etc. 

A collapsible lighl shield has been developed, which effeclively 
blocks oul any objeclionable lighl reflection. This is mounted on Ihe 
film-gale, bul in no way hampers Ihe Ihreading of film inlo Ihe pro- 


This camera is designed lo be used in Ihe open wilhoul sound-proof 
covering for ordinary shols; lo be adaplable for use wilh 65 mm. film; 
lo be readily convertible lo accommodate Ihe special 62 and 70 mm. 
films wilh which some producers are experimenling ; lo be used for 
laking colored piclures in Ihe camera wilhoul any alleralion; lo be 
suilable for recording sound direclly in Ihe camera if so desired; and 
for using 35 mm. film (Fig. 16). 

The camera is normally buill for Ihe slandard 65 mm. film. A 
special movemenl for 35 mm. film has been developed, and Ihis move- 
menl is interchangeable wilh Ihe 65 mm. movemenl. Two inter- 
changeable sprockel and roller assemblies have been developed. One 
is for 65 mm. super-film and Ihe olher for 35 mm. film, which are 

By removing one movemenl and sprockel assembly and subsliluling 
Ihe olher, Ihe camera can be used for eilher size film. This fealure ap- 
plies lo any olher size film as special movemenls and sprockel assem- 
blies can be furnished for any size film up lo 70 mm. 

In regard lo Ihe magazines, relalive lo Ihis change in film size, when 
Ihe camera is purchased for 65 mm. slandard film or for special size 
wide film, Ihe accompanying magazines are designed so lhal 35 mm. 
film can also be used in Ihem. This is accomplished by providing Ihe 
film rollers wilh a relief so lhal Ihe 35 mm. film is properly guided inlo 

* Fearless Camera Corp., Hollywood, Calif. 

Sept., 1931] 



the magazine, and by furnishing special take-up spools for the narrow 
film. These spools hold the film centrally in the magazine and prevent 
it from creeping to one side or the other. 

Standard 35 mm. magazines can also be used on the camera when 
using 35 mm. film, making it possible to use some of the existing 
equipment of the producer. This is accomplished by a special adap- 
ter which fastens on top of the camera. This adapter partially covers 
the hole for the large size film and excludes all light from the inside of 

FIG. 16. Fearless silent film recording camera showing interior design. 

the camera when using the 35 mm. magazines. With the adapter in 
place, standard 35 mm. magazines can be used. 

Other features furnished as standard equipment with this camera 
include a quick focusing device; full force feed lubrication to all 
major driven parts; and two built-in footage counters. As special 
equipment, the camera can be furnished with a built-in speedometer, 
a built-in, three-speed, high-speed gear box, and a built-in sound re- 
cording mechanism. 


A standard silent movement of enlarged size is used to feed the film 
intermittently past the aperture. Two claw pins are used on each 
side of the film to pull it down and pilot pins are used to lock the 
film during the exposure. This movement is easy to thread and, due 
to the simplicity of design and accuracy of workmanship, is so silent 
that only by placing the ear against the frame of the movement can 
any sound be heard while in operation. 


This new lamp is composed of four units: the enclosing housing, the 
burner assembly, the combination arc controller and blower unit, and 
the heat-resisting elliptical reflector. 

FIG. 17. Ashcraft projection lamp showing interior construction (burner 
assembly in center is normally covered by a plate). 

A comparatively large motor is used for driving the arc control and 
the carbon feeding mechanism, as well as a drum-type blower rotor 
mounted on the opposite end of the arc control driving the motor 
armature shaft. The action of this rotor, which is almost silent, is to 
drive a strong blast of air through the working parts of the main 
burner or element. This blast of air, after passing over all parts sub- 
ject to the effects of the radiated heat of the arc, passes out of the 
mechanism at an opening at the top of the enclosed burner housing, 
and is driven through the lamp house stack directly above the air 

* Ashcraft Automatic Arc Company, Hollywood, Calif. 

Sept., 1931] 



exit opening in the burner, carrying with it heat and gases generated 
within the lamp house by the arc. 

The benefits of this air cooling system are: protection from oxi- 
dation of the working parts, protection of springs and heat-treated 
parts from over-heating, and maintenance of a temperature below 
the deterioration point of the lubricant. The air cooling is also 
applied to the contact shoes which conduct the current from the 
mains to the rotating positive electrode. 

The working parts, such as gearing, feeding mechanism, ball bearings, 
contacts, etc., are entirely enclosed. A plate normally covers those 
parts exposed in the burner assembly shown in the cut (Fig. 17). The 

FIG. 18. Brenkert high intensity projection lamp. 

air cooling arrangement, new contact assembly, and other features are 
in reality provided for the sole purpose of improving the mechanism to 
such an extent that it will withstand a much higher current density 
in the positive electrode than was formerly possible. 


This high intensity projection lamp has all its moving parts enclosed 
* Brenkert Light Projection Co., Detroit, Mich. 


and protected from dirt and dust (Fig. 18). All moving parts are 
lubricated and are quickly accessible for removal and replacement. 
Means are provided for continuously feeding and rotating the positive 
carbon, and for intermittently feeding the negative carbon. Care has 
been taken to make the entire feeding mechanism extremely accurate 
and the feed of the negative carbon is adjusted with an accuracy gen- 
erally greater than needed. Accurate and convenient means are 
provided for adjusting the condensing lens for focusing and the con- 
densing lens can be separately removed from the lamp house. The 
lamp accommodates a 20-inch positive carbon with continuous feed 
throughout its entire length, and a 9-inch negative carbon. The 
positive carbon is released through the outside of the lamp 
house at the rear. The positive head unit, negative unit, control 
unit, condenser unit, and the entire lamp house can be taken 
out and put back in a few minutes, without having to make any ad- 

Separate manually controlled handles for positive and negative 
carbons are provided and may be operated whether the lamp is hot or 
cold. A new type of arc striker is included which automatically 
establishes the arc and is operated at full current load without causing 
injury to the positive carbon. The arc striker permits trimming of 
the carbons in the separated position. Removal and replacement of 
4 small parts permits using the 16-mm. carbon compound for those 
who desire to use this size carbon when projecting wide film. 


This film cabinet accommodates eight 2,000-foot reels of film en- 
closed in double walls of 18 gauge steel plate. The walls are l : /2 
inches in thickness, and are tightly filled with approved plastic fire- 
proofing compound (Fig. 19). 

The fume-tight door is fitted with an automatic self -locking device 
and an adjustable plunger type self-closing door pull. Adequate 
venting area is provided directly from the cabinet through a double 
walled steel vent pipe packed with fireproofing compound A humidi- 
fier provides moisture for stored film. The top of the cabinet is 
made at an angle to discourage the tendency to use any flat surface in 
a booth or storage room for miscellaneous storage. The cabinet is 
constructed as a unit to permit using them in pairs where fire and 
insurance regulations permit. 

* Neumade Products, Inc., New York, N. Y. 

Sept., 1931] 




In editing sound motion pictures it is important that the cutter be 
able to see and hear the action and sound of each of the scenes to be 
assembled. Where the sound and picture are on separate films, this 
is done by adding a separate sound-head to the desired model of 
picture-viewer used in the past. A photoelectric cell takes the place 
of the light source within the machine, and a specially designed 
exciter-lamp unit replaces the viewing-lens, while the film is moved 
between the two much as in the picture- viewer, but continuously. 

FIG. 19. Neumade fireproof film cabinet. 

Synchronism is maintained by connecting the two units with a flexible 
shaft coupling, fitted with a slip-clutch, so that either unit may be 
operated independently. Power is supplied by two motors: the ac- 
customed variable-speed motor on the viewer, and a constant-speed 
induction motor for the sound-reproducer. The two machines may 
be operated by either motor, or both, and both motors are reversible. 
Since it is desirable that both machines be kept in perfect alignment 
with each other, they are mounted on a sturdy hardwood stand equip- 
* Moviola Company, Hollywood, Calif. 



[J. S. M. P. E. 

ped with casters, so that the machine may be readily moved about. 
In addition, this stand houses the a-c. operated amplifier for the sound 
reproducer, while the loud speaker is mounted above and behind the 
sound and picture movements. This machine is known as model UD. 
For use with single-system sound and picture recordings, where the 
sound and picture are on the same film, and for final prints of the 
double-system recordings, where the sound and picture have been 

FIG. 20. Moviola sound picture inspection device for use with pic- 
ture films which have the sound record on the same film. 

combined on a single film, it was necessary to place a sound-head be- 
hind the picture-viewer. 

In model MT (Fig. 20) the film moves continuously past both the 
picture aperture and the sound pick-up. The motion picture effect is 
obtained by means of a double walled cylindrical, rotary shutter with 
a slot, which revolves around the small lamp which furnishes the illumi- 
nation. This shutter is geared to the film motivating sprockets so as 
to make one revolution per frame on the film. The double walls of 


the shutter serve to concentrate the light on the film and improve 
the definition of the picture. The part of the film that is viewed, as 
well as the part that is scanned by the light line, is stretched over 
curved tracks. This eliminates the difficulty of keeping the film from 
buckling, which is encountered on flat tracks. The film is held and 
motivated by two sprockets, one at each end of the machine, and the 
tension of the film is assured by a tension roller placed in the center, 
between the two tracks. 

The aperture over which the film passes under the viewing lens is 
the size of a "frame," and "framing" is effected by rotating the entire 
viewing system lamp, diffuser, and viewing lens by means of a con- 
veniently placed lever. The device is regularly operated by a con- 
stant-speed, reversible induction motor which drives it at a film-speed 
of 100 feet per minute. A variable speed motor may be used and this 
machine may be run at very high speed, if desired, without danger of 
damage to the film or to the machine, but running at low speed is not 
desirable with this machine, as the principle of its design allows only 
one short flash of light per frame to reach the observer's eye, resulting 
in flicker when the speed drops below a certain value. The entire 
assembly is mounted upon a metal case, which contains the amplifier, 
the transformer for the 6-volt lamps, and the connecting and switching 

A standard 50-cp. automobile headlight bulb, which is used in all 
the sound heads of the "Moviolas" as an exciter lamp, is used in this 
Model MT also as the viewing lamp, and operates from the same trans- 
former as the exciter lamp. The latest development is a "Moviola" 
projector specially adapted for editorial work with sound equipment 
for sound on separate films as well as on composite film (Fig. 21) . 

There are two separate sound pick-ups, operating through a com- 
mon amplifier. Either of these pick-ups may be used, and reproduc- 
tion may be switched from one to the other by throwing a switch. 
The two units are each operated by a separate motor, a constant- 
speed motor for the sount unit, and a variable-speed motor for the 
sound-and-picture unit. Both motors are reversible, and the units 
may be run independently or synchronously, by means of a flexible- 
shaft coupling with a slip-clutch connection. The motors are con- 
trolled by either hand or foot controllers. 

The lamp house of the projector is of the same design as that used 
for the exciter lamps of the sound pick-ups and the lamp used is 
the same, a standard 50-cp. automobile lamp. The illumination is 



[J. S. M. I>. K. 

sufficient for a picture three or four iVrt wide at a distance of I to 
30 feet, according to the focal length of the objective lens used. The 

I' K.. 21. Sound picture inspection pro- 
jector for examining picture films \\liicli 
have their sound record on another film. 


take-up devices are equipped with ratchets and automatically take 
care of the film when the direction of operation of the projector is 


Ray tor Lenses. A new series of photographic lenses has been de- 
veloped especially to meet the ideas of the cinematographer working 
at a speed of //2.3 and a range of focal lengths from 35 mm. to 152 mm. 
Tests have shown that these lenses are ideally corrected for use with 
Mazda lamps and the new high-speed film. 

FIG. 22. Mounted super-cinephor lenses and cinephor condensers No. 5124 

and No. 5125. 

Super- Cinephor Projection Lenses. These lenses are the first truly 
anastigmat projection lenses to be offered, and are notable for 
the quality of image flatness of field, definition, and freedom from 
color fringes. They were developed to meet the anticipated demand 
for wide film, which would require lenses corrected for twice the angle 
compared to their use on 35 mm. film. More recently these have 
been developed in focal lengths down to 2 inches so that there is now 
available a series of short focal lengths for use with standard film that 
makes possible the projection of the large size picture now in vogue in 
many of the theaters with a quality of image heretofore impossible. 

* Bausch & Lomb Optical Co., Rochester, N. Y. 


Super -Cinephor Condensers. These condensers have been specially 
developed for use with high intensity arcs producing from 50 to as 
much as 100 per cent increase in illumination with very uniform 
distribution over the entire field. The rear condenser of 5 '/2-inch 
diameter has a rear surface of convex cylindrical form, and a front 
surface of parabolic form. The front lens of 6-inch diameter has 
had a meniscus rear surface and a parabolic front surface. 


Summary. The use of portable and semi-portable sound recording equipment is 
gaining favor because these types provide much more flexible and economical arrange- 
ments than are possible with permanent installations. Some of the units are installed 
in trucks which can move from one location to the other with great facility. Other units 
employ portable monitors mounted on platforms which can be moved about the studio 
from stage to stage and are used in recording either with truck or permanent installa- 
tions. The paper briefly discusses the advantages of the portable type of equipment. 

A few motion picture studios are now making considerable use of 
portable sound recording trucks in conjunction with specially con- 
structed sound stages that are not equipped with permanent recording 
installations. When sound recording was first introduced the por- 
table units were considered suitable only for use on location. 
Elaborate permanent recording channels were built to operate from 
the sound stages, and because of the high cost of the building neces- 
sary to house these permanent channels and the relatively large 
amount of apparatus that was required for them, the investment was 
truly enormous. It was soon realized that it would be far more prac- 
ticable and less expensive to use portable sound trucks for recording 
on stages than to equip each stage with its own permanent in- 
stallation. This arrangement proved to be a simple solution of the 
problem of reducing the cost of equipment, and in addition provided 
a more flexible recording system, as it left the sound trucks available 
for use on location when not needed at the studio. 

The sound stages intended to be used with the portable recording 
units are generally somewhat smaller than those connected with the 
permanent installations. Usually several of these stages are built 
adjoining and massive sound-proofed doors are installed in the walls 
between adjacent stages. When it is necessary to build a large set, 
the doors are thrown open, converting the several smaller stages into 

* Presented in the Symposium on Sound Recording at the Spring, 1931, Meet- 
ing at Hollywood, Calif. 

** Universal Pictures Corporation. 


390 CHARLES FELSTEAD [j. s. M. P. E. 

a long stage great enough to permit the construction of very large 
sets. The doors are ordinarily kept closed in order to permit the 

FIG. 1. A portable sound recording truck operated in connection with 
a sound stage. The cables connecting with the monitoring equipment 
inside the sound stage are plainly visible. 

stages to be used individually by several smaller picture companies. 
The construction of the foundations, walls, and roofs of the stages 
follows standard practice in sound stage design. Special care is taken 


in designing the walls and doors between stages to make them as 
sound proof as possible. They are generally made of double the 
usual thickness, with insulating blankets hung on both sides to fur- 
nish the required acoustic effects. A sloping roof built against the 
outside wall of each stage provides a shed for protecting the sound 
truck from the weather. Where several stages are located in a row, 
the sheds are all built on the same side of the stages so that the 
trucks can be shifted from one stage to another and to permit one 
man to take care of the charging of the batteries of all the trucks 
when they are not being employed for recording. 

The cables for the monitoring equipment and for the motors that 
drive the cameras enter the stage through a small opening cut in the 
wall. The edges of this opening are heavily padded to prevent sound 
from going through. The usual portable monitoring equipment 
is generally employed for controlling the sound level at the input of 
the recording apparatus on the truck, but in some cases these stages 
are equipped with small movable monitoring booths or with per- 
manent monitoring rooms built into the wall of the stage. These 
special monitoring booths and rooms are connected to the recording 
equipment on the sound truck by plugging the truck monitor cables 
into jacks built into the sides of them. 

The trunk-like case in which the usual portable monitoring equip- 
ment is compactly arranged serves to protect the apparatus when it is 
being transported on the sound truck from one location to another. 
Two standard three-position mixing panels are mounted in the upper 
part of the monitoring trunk, permitting as many as six microphones 
to be employed at one time. The lower half of the trunk supports the 
control panel which carries the six special jacks into which the cables 
from the individual microphones are plugged. The main volume 
control, the volume indicator meter, the voltmeter for the filaments 
of the tubes in the condenser transmitter amplifiers, the six filament 
switches and the filament rheostat, and the two jacks for the cables 
that connect the monitoring equipment with the amplifiers and re- 
cording apparatus on the truck are also mounted on this panel. A 
single-stage booster amplifier is installed in the lower part of the 
trunk, equipped with a fixed filament resistor so that no adjustment 
of this amplifier is necessary. A special high-quality monitoring 
headset connected across the output of the recording amplifier in the 
truck is worn by the monitor man. 

An improved form of semi-portable monitoring equipment which 


[J. S. M. P. E. 

has been used in the Universal Studios for several months has proved 
to be unusually convenient and satisfactory. Although this equip- 
ment is arranged so that it can be connected to the permanent re- 
cording channels, it is designed primarily for use on the special 
sound stages with portable recording units. It is sufficiently port- 
able to be moved from stage to stage with ease but is not intended 
for use out of doors. The cabinet housing the equipment is of wood 
and resembles an old-style roll-top desk. A single three-dial mixing 

FIG. 2. Semi-portable monitoring desk for stage recording. 

panel is mounted in a sloping position inside the desk. Only one 
mixing panel is used as it has been found that it is very unusual for 
more than three microphones to be required at one time. The main 
volume control is placed to the right of the mixing panel, and the 
volume indicator meter just above it. The voltmeter and rheostat 
for regulating the filaments of the tubes in the microphone amplifiers 
are mounted in line with the volume indicator meter. Below them is 


a plate of signal lights and an adjustable attenuator. The signal 
lights are operated when the desk monitoring equipment is connected 
to a permanent recording channel but buzzer signals on the inter- 
communicating telephone system are used for signaling when the 
equipment is employed as the mixer control for a portable truck. The 
attenuator is in the headset circuit, permitting the monitor man to 
adjust the sound in the headphones to a volume that he considers 
commensurate with the deflections of the volume indicator meter. 

The three-stage booster amplifier, a small jack bay that permits 
various combinations of apparatus to be obtained by means of patch 
cords, and the jacks that receive the cables from the microphones and 
from the recording system are mounted in a recess in the side of the 
desk. Only three jacks for microphones are provided ; but four jacks 
are provided for the cables that connect the monitoring equipment 
with the recording channel. Two of the latter are employed when the 
equipment is used with a permanent recording channel, the other two 
jacks being employed when a portable recording unit is in service. 
Two sets of connection jacks are needed on account of the dif- 
ferent arrangements of the battery circuits in the permanent and 
portable recording channels. The storage battery that supplies the 
filament current to the tubes in the condenser transmitter amplifiers 
and the booster amplifier, and the dry batteries that furnish the plate 
potential for the tubes in the microphone amplifiers are placed in 
boxes beneath the monitoring desk. The desk and a chair are 
mounted on a platform equipped with wheels so that it can easily 
be moved about. 

One of the advantages of the portable type of monitoring equipment 
is that it can be placed close to the microphones on the set, making the 
microphone leads short. Since the electrical level of the speech cur- 
rent is raised by the booster amplifier, the speech current that passes 
through the long transmission line from the monitoring equipment 
to the recording amplifiers on the sound truck will be at a much 
higher level than it would be if the monitoring apparatus and booster 
amplifier were situated in the sound truck. The ratio of signal to 
noise picked up by the line is therefore greater than it would be if the 
signal level in the transmission line were at a lower level. 

A single portable recording unit equipped with a desk-type mixer 
control can take care of several sound stages. When a company 
that has been shooting on one stage has finished with the set, it can 
move to another stage where the next set has been prepared for it, 


taking along the portable sound recording unit. With this arrange- 
ment, the production company does not have to wait until the first 
set is torn down and the next one erected in its place. Another ad- 
vantage of the portable recording channels is that the sound truck 
equipment is much simpler and less likely to cause trouble than the 
permanent recording equipment. It occupies no ground space per- 
manently, and a smaller crew of men is required for its operation and 
maintenance. By providing two crews to a truck, it can be em- 
ployed for recording on one stage in the daytime and on another stage 
at night, thereby making the sound equipment do double duty. When 
a portable unit breaks down it is replaced in a few minutes by another 
truck and the shooting is continued with practically no delay and 
the defective unit is repaired by the engineering staff of the sound 
department at their leisure. This new arrangement is gradually 
supplanting the permanent recording channels for all recording work 
other than dubbing and the scoring of music, which are done on per- 
manent channels and in special scoring stages. 

It is likely that semi-portable sound equipment may soon almost 
entirely replace both permanent channels and the more cumbersome 
and expensive portable recording trucks used on the studio lot, as 
compact recording equipment is now being developed that is so light 
in weight that it can be placed on a small hand-truck and be easily 
moved about the studio. This new recording equipment has proved 
to be highly efficient and easy to handle despite its small size. The 
portable sound trucks will have to be retained, however, for use on 
location at points distant from the studio where rugged, readily- 
transportable equipment is required. 





Summary. This paper briefly discusses the need for standardization of the 
picture aperture of cameras and of camera motors. It is pointed out that great 
disadvantages arise through the use of freak or un-standard equipment, particularly 
with regard to the great variety of blimps now in use. The paper points out the 
necessity for standardizing the width of film and the width to height ratio of the 
picture, and for continually acquainting the cameraman in simple language with 
current progress in the art with relation to matters which involve the camera. 

Complications in the cinematographic process due to the adoption 
of talking pictures are in a sense inevitable, but certain phases of the 
new order having to do with the chaotic condition of the camera 
equipment call for remedial action. The cinematographer is cer- 
tainly carrying too much baggage, and is wasting his efforts on too 
many details unrelated to the photographic process to be able to do his 
best work. 

It is to be expected that as the scientific structure becomes more and 
more involved, the cinematographer should become more technical 
minded. There is no harm in this if it can be accomplished without 
affecting his practical outlook, and his sensibility and feeling for the 
artistic and dramatic which has such a great bearing on his work. 
For instance, much of the profound investigation in the higher 
reaches of the photographic art may be safely entrusted to those who 
specialize in research if they will but turn over to the cameraman in 
plain language any bits of practical information that they may 

The complications that are giving rise to the greatest harm are 
those that revolve around the operation of the freak camera equip- 
ment now in use. At the root of this evil lies the lack of a standard 
aperture, as well as the lack of a standardized camera motor, which is 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Hollywood, Calif. 



hampering, if not altogether checking the development of new silent 
cameras. Until this development takes place the whole array of 
queer camera blimps must continue to keep down the efficiency of the 

An attempt at determining a new standard aperture must, indeed, 
be possible at this time. The subject has been discussed at great 
length, and many solutions have been attempted. The lines are 
quite well drawn. The principal points to be considered are : 

(1) Shall 35 mm. be retained as the standard international width of 
film? (2) Is the present sound track a fixture? (3) Should the 3 by 
4 picture be retained as the international standard? 

If all these questions must be answered in the affirmative, the re- 
sult is a projection aperture substantially 0.600 by 0.800 inch and a 
negative aperture only slightly larger. 

If the above questions can be successfully contested here and there, 
the way is open for an improved set-up. The cinematographer 
naturally wants the size and proportion of the picture that will give 
him the best technical and artistic advantage, but above all, he wants 
a definite settlement. Aside from clearing the decks for action in re- 
gard to new construction, he needs the assurance that his picture will 
reach the screen without changes in shape or size. At the present 
time the head-room is an unknown factor and to vignette would be 

Progress, too, awaits the standardization of the camera motor. 
Due to the fact that the motor may have to be built into the camera 
in order to achieve the utmost quiet, every effort should be made to 
standardize at least the size of the motors, their speed, and their 
mounting, so that they can readily be interchanged for any system of 



MR. FEAR: The problem of camera motors goes somewhat further than 
simply the motor. A standardized motor that runs at a speed of 2,400 rpm. 
is not at all desirable for silent cameras. It is the elimination of gears and 
gearing that is the big problem in the silencing of cameras. If the producer 
would standardize on a frequency of 48 cycles he could then utilize motors which 
are available at the present time that run at 1,440 rpm. The Westinghouse 
E. & M. Co. is building an interlocking motor which is adaptable to either the 
3-phase operation or interlock systems. If we could standardize on a frequency 
which would enable us to avoid gears, we could build the motor into the camera 
and produce a silent camera motor. Any camera manufacturer will be able to 
build silent cameras, once he has a standard motor and definitely knows that 


that motor will be used. At the present time it is necessary to use an adapter 
for several different types of motors, all of which introduce complications, as 
they variously rotate at 1,200, 1,800, 2,400, and 3,600 rpm. It is impossible to 
make one adapter fit all conditions, with such a multiplicity of motors as are 
now being used. If a standard frequency is adopted we can build the camera 
motors into the cameras as an integral part of the camera, insulating them in 
such a way that they will not transmit noise, and thus be able to produce a 
camera which will not have to be used inside a booth. 

MR. DUBRAY: The question of standardizing the aperture of the camera is 
very "hot" right now. The camera manufacturers are all working toward 
standardization, at least as far as is compatible with the commercial side of the 
problem. I understand that the present situation is rather complex the Publix 
or Movietone apertures are not sufficiently used as yet in all theaters to un- 
conditionally warrant establishing either of them as a standard. We hope that 
a decision will soon be made. Standardization is a slow process, and we can 
only hope that the existing conditions will improve and that the Publix aperture, 
retaining the old picture ratio of 3 to 4 (after allowing for the necessary width 
of sound track) will be established as a standard camera aperture. 

MR. FEAR: As I understand it, the 35 mm. film is now standard. However, 
we cannot say it will remain standard indefinitely. If we change the film size, 
we should use a ratio that is esthetically correct, such as the 3 by 5 ratio, or any 
ratio the Society may decide upon. To limit ourselves at the present time to 
the 3 by 4 ratio for future development would be inopportune, I believe. 



Summary. Due to the great variation in blimps or camera covers, it is impossible 
to standardize on auxiliary camera view-finders. At the present time these finders 
are so arranged that the finder picture coincides with the photographed picture in 
but one plane, so that the cameraman cannot depend on the finder picture for photo- 
graphing the desired view. Several remedial suggestions are made in this paper, 
and the great expense caused by the lack of well-designed view-finders is briefly 

Have you ever asked a producer what the auxiliary view-finders 
are costing him on each production? What would be his reaction if 
he were told they were costing him more than all the camera equip- 
ment on the picture is worth? That would be a very broad state- 
ment ; but let us study a few of the facts and then draw our conclusions. 

First of all, just what is so entirely wrong with our present view- 
finders as to cause a great waste of time? The cause is an indirect 
one; the blimp, or camera cover, is the principal offender. There 
are few, if any, serious steps being taken to build a perfect finder for a 
camera housed in a blimp. 

In the pre-sound days when the finder was directly connected to 
the camera it was bad enough to have to re-set it for each change of 
camera set-up, but now with the necessity of using a blimp, the situa- 
tion is a serious handicap. 

On most blimps the view-finder has been moved to the outside, 
making the perspective point far to the side of the photographing lens, 
so that the finder picture coincides with the photographed picture in 
but one plane. Finders mounted in this manner are usually very 
flimsy affairs, and cannot be trusted even under favorable circum- 
stances. Some companies have favored the idea of building the blimp 
around the finder and camera combined, producing the monstrosity 
commonly known as the "bungalow." 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Hollywood, Calif. 


A very desirable form of finder would be one built into the blimp 
as a permanent unit to fit the camera. Attempts along this line 
have been made by placing the finder lens about six inches directly 
above the photographic lens. This form, however, has a bad vari- 
able head-room, together with the very serious difficulty of being un- 
able to shade off the blimp glass or photographing lens without cut- 
ting into the top of the finder picture. The only solution for this is to 
shade off with black flats far back in the set. Then with a three- 
camera set-up it becomes a problem to rearrange all the top lights to 
fit the shades. 

Let us take any camera crew and watch them worry over the setting 
of finders. You will find it a very interesting procedure, as they do a 
lot of apparently unnecessary work over and over again, as often as 
the camera is set up. Even after all this painstaking work, the cam- 
eraman can only trust to luck that he is photographing what he sees 
in the view-finder. This procedure wastes valuable time time that 
operates on the cost of production. The present equipment, with 
finders that are neither accurate nor dependable, must be carefully 
checked at the last minute before shooting, while the whole troupe 

From observations covering several camera crews at various stu- 
dios, a very conservative estimate has been made which would charge 
directly to finder equipment at least forty minutes per day of produc- 
tion time. This is based on eight set-ups per day using two cameras. 
It does not include the many times per day that it is necessary with 
present equipment to throw over and look directly through the camera 
to check microphones, etc. 

Consider forty minutes a day; a twenty-eight day picture; the 
salaries of the entire troupe and the cameraman. 

Why not stop all this waste? A finder can surely be built that 
would have all the good features and none of the bad. It is only 
necessary to build one with the present upright, well illuminated field 
having the same perspective as the photographic lens, or within two 
inches of its axis. It should have a micrometer adjustment, visual 
footage indicator, and the same size field for all focal lengths. Such 
an instrument will allow instant adjustment and give the camera 
operator a full-field finder picture of the exact area being photo- 

That does not sound difficult, but consider how many kinds of 
cameras there are. Not many, true enough, but consider the great 


variety of blimps. There are scarcely two alike. It is a case of an 
individual design job for each camera. Before we begin to re-design 
them we must agree upon a suitable model and standardize equip- 
ment to conform to it. Cameramen have studied this problem since 
the introduction of sound, and many of them have evolved construc- 
tive ideas. The S. M. P. E. or the Academy should appoint a group 
of such cameramen to work with the camera manufacturers to 
straighten out the situation. 


MR. PALMER: In connection with this matter of the view-finder, I would like 
to suggest the obvious advantages of the old Debrie camera in which the image 
which was actually going to be photographed on the film could be seen directly 
through the back of the camera, not only while setting up the camera on the 
scene, but during the actual photographing of the scene itself. 

MR. FEAR: I believe Mr. Baker has not sufficiently investigated the matter 
of the wide angle matte box. I believe the Mitchell Camera Company makes a 
wide matte box, and I know we make one that can be used on the standard camera. 

The cameraman needs two types of camera one for studio use and one for 
newsreel use. The newsreel type is highly desirable for recording when a camera 
is required for recording within the camera without separate recording means. 
The Western Electric Company has an adaptation of the Akeley movement in 
their design. The question of motors is not as serious, as we can furnish a silent 
motor, provided the studios will agree to use a standard frequency of 48 cycles. 



Summary. This paper deals primarily with the need for improving the 
design of cameras and camera accessories. Existing photographic equipment is 
reviewed and the inefficiency of blimps and camera covers is stressed. The remedy 
for the situation evidently lies in the standardization of motors and the adoption of 
silent movement cameras. The paper closes with a summary of views on the matter 
by leading first-cameramen of the industry, and suggestions for changes in existing 
accessories, to be embodied in cameras for the future. 

Since the advent of sound it has been evident to cameramen that 
something must eventually be done to provide modern photographic 
apparatus in order to cope economically with the radical changes 
brought about in studio production. 

All cameramen in studio production are forced at present to work 
with out-of-date equipment. Much progress has been made within 
the past year, but that progress has been rather of a makeshift variety. 
Little actual constructive advance has been made in photographic 
apparatus since the pre-sound days. 

Clumsy and cumbersome boxes have been built for shielding from 
the microphone the noisy cameras and motors, instead of directing 
that effort toward the perfection of mechanically silent equipment. 
Every day producers of motion pictures are losing thousands of dollars 
due to their reluctance to spend relatively small amounts for silencing 
and standardizing camera equipment. 

At least two camera manufacturers have carried on extensive cam- 
era and motor silencing experiments on their own initiative to such an 
extent that they will be able within a few short months to begin whole- 
sale production of suitable equipment. There is, however, one dis- 
couraging factor which they all face ; that is, a standard motor. 

It may be said that the number of different motors can almost be 
determined by enumerating the producing studios. It is evident 
that little progress will result from operating the finest silent 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Hollywood, Calif. 


402 IRA B. HOKE [j. S. M. P. E 

camera movements by fair, noisy, or indifferent motors. It makes 
little difference which of the recognized standard systems is adopted, 
so long as producers unite their efforts toward the perfection of the 
selected unit. Camera manufacturers, of course, prefer a camera- 
speed motor as a nucleus. 

The producer is inclined to figure that since he has spent thousands 
of dollars muffling the noise of old-fashioned cameras, his responsibility 
in the matter ceases. But not so. 

Last March the Academy of Motion Picture Arts and Sciences sent 
out a questionnaire to first-cameramen engaged in production. Of 
the sixty questionnaires returned, 91 per cent advocated strong efforts 
toward the development of cameras which will require neither blimps 
nor covers. These cameramen represent every studio in Hollywood. 

Ninety per cent condemned blimps or covers because of their weight 
and 87 per cent because of their bulk. Over 50 per cent stated that 
covers made focusing difficult. Practically every type of deadening 
device in Hollywood was criticized for one or more of these reasons. 
These are the opinions of the men who are close to the seat of the 
trouble. They all tell the same story inefficiency, lost motion, 
untold valuable time sacrificed in order to salvage antique 

The time has come when cameramen must insist on more efficient 
equipment, and the producer must see that the camera manufacturers 
provide it. 

This patently requires a total revision of existing cameras, and we 
should be certain of our steps before we proceed. For instance, if we 
should merely remodel the present camera, we would find ourselves 
struggling again with un-standardized details, small gadgets not 
usually thought of as essentials, but great time savers or time wasters, 
as the case may be. Let us, therefore, itemize a few of the lesser de- 
tails which should not be overlooked in our quest for silent movements 
and noiseless motors. 

Movements should, of course, provide register pins, a convenient 
cleaning arrangement, and positive roller contact. A standard aper- 
ture should be agreed upon and suitable masks provided and used, so 
that only the composition originally made by the cameraman could be 
projected. This is, in itself, a simple matter, as there are required 
only an aperture mask for the camera and a similar one for the 
projection machine. At present, various cameramen are framing for 
Movietone, Academy Standard, and full-screen proportions. It is 

Sept., 1931] THE CAMERA OF TOMORROW 403 

evident that projectionists are at times unable to present the picture 
as originally composed by the cameraman. Here, again, is an 
example where only the producers can help themselves. It is a case 
of agreement on standard only. 

A combination buckle trip switch, instantly adaptable to either 
synchronous or non-synchronous motors, will save untold time and re- 
pair expense. This trip is a device which throws a sensitive switch 
the instant the film fails to take up properly after being exposed. 
Buckle trips now in use break the motor contact before six inches of 
film are out of place, the camera stops, and severe damage is avoided. 

Multiple-length dissolve mechanisms are features of almost every 
camera and by all means should be retained. 

In order to compensate for the weight added by integral motors as 
well as the extra weight necessary in the modern wide aperture lenses, 
it has been suggested, wisely, that the quadruple lens turret be elimi- 
nated in favor of a light frontboard provided with a quick-acting quad- 
ruple screw-thread. The base of each lens mount would embody a 
companion screw-thread to fit accurately in place on the frontboard 
with a two- or three-turn movement. This arrangement would allow 
a more rapid change of lenses, a more positive and rigid lens base, 
and would also enable the cameraman to rapidly select any focal 
length desired without encumbering his camera with heavy equip- 
ment only occasionally used. 

Then comes the question of more careful selection of lenses. At 
least one company has employed a widely experienced lens expert who 
makes photographic tests of every lens purchased by the company 
before it goes into actual use. He is certain that each lens is optically 
efficient for use in the modern motion picture studio. 

Optical systems providing for eye focus and line-up of photographic 
composition, are at present highly perfected. However, the view- 
finder, through which the action is watched by the cameraman during 
actual takes, is due for improvement. The best of these in use today 
is separated by several inches from the axis of the photographing objec- 
tives, thus rendering a correct view of the composition at only one dis- 
tance from the camera. These finders are provided with a single 
lens. The field of view changes rapidly with change of focal length 
of photographing lenses, and this is compensated for in the view- 
finder by a series of mats with an opening to correspond to the field of 
the lens being used. On the face this appears satisfactory, but in the 
case of long focal length lenses, where greatest accuracy is required, 

404 IRA B. HOKE [J. S. M. P. E. 

the field of view becomes too small. Such finders would profit 
materially by a wider range of objectives in order to provide a larger 
image on the working ground glass when 4-, 5-, and 6-inch lenses are 
being used on the camera. One cameraman has provided himself 
with a separate finder embodying this principle, for use with lenses 
having focal lengths greater than 50 mm. He has fitted this finder 
with a 6Y2-inch lens which allows large aperture mats to be used 
when the longer focal lengths are used. 

The ideal method of watching the picture during the take would be, 
of course, by means of a reflected image taken directly from the photo- 
graphing lens. Several manufacturers have seriously considered this 
step, and in the case of one studio a wide gauge camera was built last 
year successfully applying this feature. 

Mat boxes, or sunshades, have in the past, and do today, lack 
versatility. That is, in order to use the wider angle lenses on the 
camera the operator must entirely remove the device in order to pre- 
vent its sides from cutting into the edges of the scene. The remedy 
for this is simple and of no moment mechanically. It entails merely a 
larger model of the present design. Several cameramen have built 
their own models successfully, but at present no manufacturer pro- 
vides such a unit. 

A few weeks ago an enterprising inventor startled the industry by 
embodying in his late model camera a built-in automatic exposure 
meter. The camera of the future should without fail incorporate such 
an instrument. The efficacy of a completely automatic meter is un- 

Two companies have produced gyroscopic tripod heads which are of 
inestimable value hi panorama and close-up shots. These tripod 
heads allow the cameraman a smooth, easy, floating control of his pic- 
ture composition at all times and under all circumstances. Scenes 
made with the gyro tripod tops are noticeable on the screen by their 
liquid moves in framing up or down for head room and for their easy 
allowance to actors of a natural freedom of side movements on large 

These are but a few suggestions of details necessary in the camera of 
tomorrow. Today's camera is a hodge-podge of mechanical gadgets 
that have been screwed on in convenient places. It has been a 
good camera for us to learn with, but now that we know what is 
necessary to photograph successfully the modern screen play we 
must discard our beginner's tools and build an instrument worthy 

Sept., 1931] THE CAMERA OF TOMORROW 405 

of the greatest era yet to be witnessed in the amazing growth of the 
cinema tomorrow . 

Before the change-over of cameras is made by the producing studios 
it is, therefore, advisable to appoint a committee of recognized first- 
cameramen to pool their ideas of mechanical features to be adopted in 
the new instrument. If such procedure is followed the manufacturers 
will be enabled to standardize cameras that will stand the test of 
efficient service for many years. 


Summary. A historical introduction, outlining the various stages of development 
of motion picture photography; progress in the manufacture of materials; innovations 
in technic; changes in the design of equipment, lighting systems, etc. The present 
school of photography is facing a most unsatisfactory period, with its excessive amount 
of interior work and elaboration; the art is developing too rapidly to permit cine- 
matographers to thoroughly master it. Great restraints are placed upon the camera- 
man by the recording of sound, and the camera covers are a serious handicap to his 
artistry. The super sensitive film gives promise of an era of better photography, 
permitting improvements in exposures and lighting system The use of filters is but 
imperfectly understood by the cameraman; and motors, apertures, etc., must be 
standardized before any considerable improvements in camera design can be realized. 
The need for photometric devices and other scientific measuring instruments is em- 
phasized, the lack of such facilities causing a degeneration of the photographic art to a 
system of guesswork. 

Many students of the various forms of art have considered it a good 
method of study to review particular periods of development, search 
out the secrets of individual mastery, and classify definite schools of 
treatment. Such a course of study may aid in the solution of the 
current problems of a like art. The acknowledged merits of one ex- 
ample may point out the errors in another. A thorough analysis of 
these merits may furnish ideas that the student may apply to his 
present study, from these ideas developing new ones, suggesting new 
needs, and acquiring a greater degree of perfection in his art. 

When we speak of the student we refer to the type of mind that 
leaves nothing unturned that might add to his enlightenment. Let 
us not fear, then, to go back to the daguerreotype or the wet plate, 
even if these do nothing more than to inspire a just appreciation of 
the photographic materials and facilities in use today. 

But what is more important, we may find in such a retrospect much 
evidence of sufficient merit to show very clearly the magnitude of 
the responsibility that devolves upon the cinematographer of the 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 
** Hollywood, Calif. 


present time. This evidence becomes very significant when we 
enumerate the comparisons between modern materials, equipment, 
and facilities, and those of former times. In such a survey we take 
no notice of that early period when the mere novelty of motion 
pictures excused and permitted all kinds of photographic efforts. 
We rather consider the beginning of the post-war period, when 
motion picture photography developed into a really beautiful art. 
It may be interesting to review some of the agencies of this de- 

Some of the pioneers were beginning to learn the powers of their 
medium. The very beauty of the thing was beginning to enlist fine 
talent peculiarly fitted for the art. Contributions made by one 
class of investigators stimulated others. Projection was improved; 
the laboratories moved from dirty sheds and cellars into handsome 
buildings equipped for better processing. The manufacturers re- 
sponded with improved cameras, new and varied lenses; the old 
static-generating film was replaced by the X back and, shortly after, 
that was improved. The open air, diffused sunlight stages gave way 
to inclosed ones with their limitless combinations of artificial light. 
Directors and cameramen, alike, enjoyed the full range of their me- 
dium. The pictures abounded with beautiful outdoor scenes and 
spectacular light effects. The industry prospered and offered gener- 
ous encouragement to the most earnest efforts toward artistic develop- 
ments. All this resulted in that period of interest which we are now 

It was likewise a period of experimentation. Everyone experi- 
mented, and the results were astounding. Novelties were introduced 
with breath-taking swiftness. Successful experimentation furnishes 
the most stimulating influence on the mind of man, and urges him to 
achieve still more. Nothing stops him except the inviolable laws of 

All these developments so broadened the cameraman's means of 
expression that he began to exhibit a definite individuality. He had 
become an artist; his manner of vignetting, his system of lighting, his 
soft focus effects, his exterior compositions were thoroughly char- 

Still he was not satisfied. He wanted to do things yet denied him 
to go into shadowy places which his 4.5 Heliar had heretofore pro- 
hibited; to produce more satisfactory night effects; to photograph 
the clouds hanging over the mountains ; to render color in proportion 

408 LEWIS W. PHYSIOC [J. S. M. P. E. 

to its effect on the eyes. He had to have faster lenses, and highly 
sensitive panchromatic film. 


The acquisition of these new, or improved, elements ushered in a 
new style of photography, and for the next few years, according to 
some critics, motion picture photography appeared to be less satis- 
factory than at any time since the early stages of its development. 

The reasons for this condition are worthy of study. There de- 
veloped a great tendency to shoot pictures on the lot or on interior 
settings, and as a result the pictures lost their charming variety of 
interplay between beautiful exteriors and adequate interiors. Simple 
beauty and tasteful elegance were submerged in competitive display 
and elaboration, and in complicated photographic effects. 

The new wide aperture lenses were difficult to manipulate. There 
was a considerable amount of faulty focusing, from which developed a 
careless distinction between the legitimate diffused effects and real 
errors of focus. The broad-faced lenses were also difficult to mask, 
and tended to flare and veil the image. 

There developed a marked tendency to overexpose, in order to 
secure "softness" an exaggerated use of shiny reflectors on exteriors 
and too much front light on interiors, neutralizing the effect of the 
principal sources of light, as of special accents. 

This tendency required an appropriate modification of laboratory 
treatment. Although developing formulas were greatly modified, 
nothing more was done than to provide printing densities by super- 
ficial development. In many cases the entire printing systems had to 
be changed. All these changes, it is reasonable to suppose, may have 
developed an entirely new taste for, or judgment of, quality; this we 
can determine only by a review or comparison of past performances. 

All this may appear critical, but we can reasonably plead extenua- 
tions in the matter. We have developed too rapidly. The camera- 
man had advanced to a higher state before enjoying, for a while, his 
mastery of current conditions seeking innovations before exhausting 
the existing novelties. 

A great financier in analyzing production problems has said that 
twenty-five years should have elapsed before giving us the pan- 
chromatic film, fifty years before giving us the color pictures, and a 
hundred years before giving us the talkies. But to return to our 


Picture production was becoming an elaborate display. There 
is nothing which frightens the rank and file of workers so much as the 
responsibility of spending vast sums of their employers' money. Re- 
takes are costly, the time of making them is more so. There is a 
temptation to insure one's position by using every available element 
of the process of making pictures. 

The introduction of the panchromatic film and incandescent light- 
ing staked out a new milestone on the road of progress of the art. 
They demanded more of the cameraman's skill. They brought him 
face to face with a deep and complicated branch of science from which 
he was heretofore exempt the theory of color. Many able photog- 
raphers freely expressed their uneasiness over this new phase of 
their profession. Others welcomed the new system with bold assur- 
ance ; and some achieved such success as to prove, beyond a doubt, the 
value of the new material. 

In bringing our retrospect up to date, we believe that there is still 
a tendency to overexpose. Photometric readings have been made in 
various laboratories that disclose the fact that the great majority of 
negatives, both exterior and interior, are printing on the heavy side. 
And what is more important, the negatives do not have the appear- 
ance of being fully developed, leading to the belief that the machines 
and developers have been adjusted to secure a printing density at a 
sacrifice of quality. There have even been instances where it was 
necessary to dupe negatives in order to print them. 

The dupe furnishes another reason for what may appear to be 
a hypercritical attitude. A dupe is a dupe, no matter how well 
made; and the amount of duping done in the last few years cannot 
but have shown its effect on the general quality of the pictures. 
All this may suggest that we were beginning to stray from the first 
principles of photography, i. e., correct exposure and proper develop- 


Before we had completely mastered these difficulties, talking pic- 
tures were upon us. They greatly affected the photography of motion 
pictures for very apparent reasons. The cameraman no longer has 
the freedom and the range of activity he enjoyed prior to the sound 
picture. He has had to make the best of the sound-proof booth and 
the various other camera covers. These adjuncts have restricted his 
individuality and have shrouded his artistry in a mattress like re- 
quiring a violinist to play with mittens covering his sensitive fingers. 

410 LEWIS W. PHYSIOC [J. S. M. P. E. 

There is a very unsatisfactory feeling in having to shoot through 
heavy plate glass, with its refraction and reflection, the personal 
discomfort of the cameraman, the difficulty of lining up sets and 
focusing, or following focus during the moving shots that seem to have 
become so popular. 

Many inquiries have been made as to what type of blimp is most 
satisfactory. There are no satisfactory blimps. Indeed, there is 
little improvement in the "blimp" over the "dog house" (booth) of the 
earlier days of the talkies. 


We now approach still another era in motion picture photography 
the era of the supersensitive film. The new film seems to have found 
favor among the cameramen. The reasons are interesting, and an 
analysis of those reasons should be helpful. 

Exposure. We cannot be too insistent upon a correct exposure, 
and a study of this particular situation discloses a very encouraging 
outlook. In some quarters where there has been a tendency toward 
overexposing, the work shows a decided improvement. The reason 
for this lies in the fact that the operator, knowing the great speed 
of the film, loses some of his fear of underexposing. He is lighting 
the sets more softly and is no longer afraid of shadows; and shadows 
well arranged are the life of photography. Many have returned to 
the //3.5 aperture on the studio sets, which furnishes better definition 
and improves the focal effects obtained when moving objects are 
included in a background of close-ups. All this has likewise improved 
the printing range. 

Filters. It is yet too early to consider the question of filters in 
connection with the new supersensitive film ; here again we can study 
this subject only by reviewing past usages. 

After having canvassed a number of cameramen, we have come 
to the conclusion that considerable uneasiness is felt regarding the 
use of filters. There is, apparently, a limited understanding of this 
complex subject. Many complain that the information given out by 
authorities is too technical in character for the majority to understand 

Some have successfully used the neutral filters for controlling 
exterior exposures, but they rarely go beyond the use of the 50 per 
cent filter; some have used the combination of the neutral and the 
color separators; some, who are very timid as to the use of filters at 


all, have confined their use to the great favorite combination, 23 A and 
56, for night effects. 

Others have a most complicated collection of filters, and use them 
very indiscriminately. We may fancy that there is great danger of 
having too great a variety of contrasts in their work. Among such a 
collection are numerous "trick" filters, graduated from a highly 
actinjc violet at the bottom to a deep mixture, such as the 23A and 56, 
at the top. Such a filter is supposed to render night effects, the upper 
part "holding down" the sky, while the lower part permits the fore- 
ground to register very definitely. 

We question the value of such a filter; its effects are false and are 
lacking in natural balance. Indeed, it is very difficult to obtain 
satisfactory night effects in full daylight. It seems that very little 
improvement has been made in this matter over the former method 
of carefully exposing the panchromatic film with a uniform filter and 
submitting the print to the tinting and toning process. Some beauti- 
ful effects have been achieved by this old-fashioned method. 

The knowledge of filters seems to be somewhat of a club affair. 
Cameramen like to discuss the use of this or that filter for various 
effects. The study of the subject seems to be limited to discussing the 
results of every-day experiences, and conditions are so variable from 
day to day and hour to hour that we doubt whether this is the proper 
method of study. The writer confesses that he is familiar with very 
few of the names of the various filters, but is accustomed to select 
a filter by judging it according to the prevailing light conditions, 
the name be what it may. 

There are many difficulties that enter into the use of filters. There 
is a physiological variation among individuals' eyes. They do not 
see or judge color alike. Consequently, this exchange of experiences 
is readily accounted for. 

It is generally agreed that best results are obtained by using filters 
as follows: For early morning light, up to 10 o'clock, use the K2 filter. 
For early morning back light, use Kl, modeling and obtaining con- 
trast by means of reflectors. For flat front light use K3, in order 
to increase modeling and contrast. From 10 A.M. to 2 P.M. use 
Kl with neutral arid more exposure, in order to soften the shadows of 
the midday sun. In such light the color factor is least considerable, 
and the neutral prevents the veiling of the shadows so undesirable in 
exteriors. The neutral seems also to permit obtaining good lumin- 
osity and fine detail in the shadows, and prevents clogging up and 

412 LEWIS W. PHYSIOC [J. S. M. P. E. 

spreading of the highlights. From 2 P.M. through the afternoon, 
the color of the light of declining day is very noticeable and changes 
rapidly. In such light very little correction by filters is necessary. 

Soft diffused sunlight is highly actinic and very tricky. It lacks 
contrast, and in such light colors are more pronounced. Such light 
requires about a K3 filter for color rendition and contrast. Spectacu- 
lar cloud effects, of course, require a variety of treatment according 
to formations and the distribution of colors. This matter is indepen- 
dent of the foregoing suggestions. 

The judging of the color of light is very difficult for those who 
are not particularly trained for such work. The artist must of 
necessity cultivate this. By estimating the color of the shadows he 
can determine the character of the light by the principle of comple- 
mentary colors, which establishes the key in which he must paint his 

Those who are not familiar with the theory of complementary 
colors may be interested in a few simple experiments. Cover a desk 
lamp with a piece of red gelatin and permit the shadow of a pencil 
to be cast upon a sheet of white paper. The shadow will be a pro- 
nounced green, the exact complement of the red in the gelatin. 
Replace the red by blue gelatin, and the shadow will be yellow, 
complementary to the blue. The K3 filter, covering the light, will 
cast a shadow which is decidedly violet. Therefore, when violet or 
bluish shadows cross the foreground very little filtering is needed. 

The neutral filters are very valuable, for in many instances it is 
very difficult to control the exposure without them, especially when 
the photographer dislikes the wiry sharpness of the diaphragmed lens. 
With filters, as with painting, we recommend a simple palette, Kl, K2, 
and K3, and the 23 A and 56. Some photographers seem to think 
that the new film gives best results with Aerial 1 and 2, the mono- 
chrome orange, and 23 A and 56. 

Lighting. Since the introduction of the supersensitive film there 
has been a great deal of discussion as to its influence on the amount 
of light used on the sets. Investigation discloses varying conditions. 
There has been very little reduction of current for lighting. It is 
rather early to expect that. However, there "has been a great 
deal of silking of the lights, which has invited some controversy. 
But it must be considered that the silking of the lights is not done 
for the purpose of reducing the light in lieu of saving electric power, 
but to increase the diffusion as well as to modify the exposure. 


Highly diffused light permits a fine registration of special effects, such 
as lamps, lights through windows, etc. the so-called trick lighting 

Some operators are giving the lights greater range, achieving 
greater dispersion in a slightly different manner from that obtained 
by silking, and allowing greater freedom of action and more personal 
comfort for the actors. 

There are some who have probably expected too much from the 
new film and have made the lighting somewhat too sketchy. How- 
ever, this is merely an experimental daring that soon will be cor- 

We have no doubt but that there will be great changes wrought in 
the lighting system; there is no question that there ought to be. 
Everything should be considered that may enable us to take full 
advantage of the merits of the new film stock lighting, lenses, filters, 
developers, etc. 

Make-Up. Investigation shows that there has been very little 
change in make-up to meet the conditions of the new stock. There 
is no apparent reason why there should be any great changes, excepting 
those required to correct some of the errors of the past. Some of our 
best experts have always opposed straying too far from nature. Let 
the make-up rather serve the purpose of the retouch artist. There 
is still a great deal of exaggeration in the treatment of eyes and lips. 
The greatest of care should be shown in the treatment of pronounced 
blondes. There is something very false and unnatural, especially 
in black-and-white photography, when a very light blonde is shown 
with too swarthy a face, heavily shaded eyes, and harshly penciled 

The Camera. Ever since the introduction of talking pictures the 
camera has been the cause of our greatest problems. The micro- 
phone, searching and exacting, turned out to be something the camera 
designers had not anticipated. The multitude of gears and moving 
parts make the present cameras very unfit for photographing electri- 
cally recorded pictures. A great deal of credit should be given 
those who have rebuilt them in an effort to silence them sufficiently. 
However, these alterations are merely heroic makeshifts. The in- 
creased speed at which they are driven is very trying on them. An 
entirely new idea is necessary. We believe that something already 
has been accomplished in this direction, a camera somewhat on the 
principle of the old Vanoscope, but not yet fully proved. 

414 LEWIS W. PHYSIOC [J. S. M. P. E. 

Motors. The question of motors has been a serious one. They 
must be standardized before the engineers can make up their minds 
what to do about the camera. At present the personnel of each 
studio seems to have its own ideas about the type of motor to use. 
Another difficulty in the way of camera developments is the uncer- 
tainty of the picture aperture. This must also be settled before 
anything can be done. 

The Aperture. The present picture dimensions cause considerable 
worry for the artist. It is very difficult to frame a good picture in the 
present aperture with its awkward proportions. Vignetting and 
other effects are prohibited by the limited areas. Projection aper- 
tures are not standardized, and the cameraman is never sure of his 
frame. We frequently see the tops of heads cut off, actors partly out 
of the picture, and other awkward instances of framing. 

The tremendous cost of providing a new aperture is realized, but the 
present one is certainly unsatisfactory. Even when matted down 
to the original shape, it has many disadvantages, chief among which 
is the apparent increase of graininess by further enlargement. 

Photometers. Obtaining the proper exposure is of such vital 
importance that a finely perfected exposure meter would be of great 
help. Heretofore it has been difficult to interest cinematographers 
in such a device, but the cameraman's responsibilities have increased 
to such an extent that they would now welcome anything that will 
aid them in estimating exposures. Such a device would enable the 
cinematographer to devote more time to the purely artistic features 
of his picture. 

Spectroscope. There has been an interesting attempt to design a 
spectroscope to aid in the selection of niters, but the experiment has 
not been carried far enough. This is probably due to the designer's 
lack of knowledge of the cameraman's needs. A slide has been 
provided into which a filter may be inserted, to furnish by this 
means a comparison of the spectrum with and without the filter. 
However, a very keen judge is required to determine how much and 
what portion of the spectrum is modified. 

If such an instrument could be elaborated to furnish a scale that 
would show clearly the shifting of the bands of color and the varying 
character of the light, the operator might be enabled to choose a 
filter of the proper factor to compensate for the quality of light. 

Standardization. Photography has long been an art which has 
depended to a great extent on one's personal judgment, experience, 


inherent impulse, guesswork, etc. The attainment of success has 
been in proportion to the individual ability of the operator to balance 
against each other a great many very uncertain elements. The 
operator chooses his subject, sets up his instrument, and muses: 
"Well, I guess I'll close the diaphragm on this to carry that distance, 
but to prevent too much harshness I'll give it a good, full exposure. 
Then I guess I'll develop in pyro, and strive for a soft, thin negative 
with lots of detail in the shadows." When the time arrives for 
printing he guesses through another process, and when it is finished 
exhibits a marvelous piece of guesswork. 

Such efforts represent a highly individualistic art. But the making 
of motion pictures is a business which involves enormous expendi- 
tures. Nevertheless, the cameraman has to go through very much 
the same procedure as the lone artist just pictured; not, however, 
with the same limited expense of the still-picture enthusiast, but with 
thousands and thousands of feet of costly film. 

The uncertainty of his endeavors is further reflected in the labora- 
tory situation. The laboratory expert, in turn, follows with the guess 
that the developing machine should be run at such-and-such speed, 
using the accepted formula ; he is sure of but one element, and that is 
that the correct temperature is 65 degrees. 

We are trying to avoid overexposure and superficial development, 
and their accompanying gray and muddy tones. We must avoid 
underexposure and forced development, with their concomitant 
chalky whites and empty black shadows. We would like to know 
what are the ideal conditions, the full possibilities. 

There may be possibilities in our present materials not yet ex- 
plored. We would like to see experiments conducted to ascertain 
the full scope of the new supersensitive film, and for the purpose of 
establishing standards that will enable- us at all times and under all 
conditions to get the best results without too much guesswork. 

We do not know of another industry of such magnitude that so 
little encourages scientific research for the benefit of its technical 
departments. We cannot overlook the fact that we have learned 
a great deal from our brother workers in the sound department. 
They have well proved that with their more nearly standard exposures 
they can equally maintain or control the proper contrast in develop- 

What we need very badly is honest, intelligent, constructive 
criticism. There is nothing so stimulating as criticism; not the 


caustic, controversial criticism so common among reviewers, but 
competent, analytical disquisitions. We have very little of this. 
A picture is either a "knock out" or a "flop;" the photography is 
either good or bad, dull or clear. We want to know why a thing is 
good or bad. We want to know what to avoid and what to enlarge 
upon. Some of us may not relish criticism of our work, but secretly 
we will profit by it, for the real student will gather from every source. 
An artist once bitterly upbraided an associate for pointing out an 
error on his canvas, but the more he tried to justify his work the more 
glaring that fault became, and he never rested until he had painted it 
out and corrected it. 



PRESIDENT CRABTREE: I wish, first of all, to extend a hearty 
greeting to all of you from the members of the Society of Motion Pic- 
ture Engineers throughout the world ; also, on behalf of the visiting 
members of our Society, I wish to thank those who have worked so 
hard to make our Convention such an outstanding success. We have 
been overwhelmed by your hospitality, which I assure you is deeply 

It was almost exactly three years ago that we held a meeting in 
Hollywood. By looking back and comparing our status then and 
now, we realize how our Society has grown, not only in size, but in 
its value to the industry and to mankind. The comparison also 
brings home to us the magnitude of the changes which have taken 
place in the technic of producing motion pictures. 

In 1927 the tools of production consisted largely of cameras using 
orthochromatic film and arc lamps. The year following, panchro- 
matic film was almost universally adopted and, in consequence of the 
improvements in photographic quality which resulted, the producers 
began to direct more attention to the technician because they saw 
that he also was a potential contributor to box-office values. 

A study of the relative merits of arc and tungsten lamps for light- 
ing sets was instigated by the American Society of Cinematographers 
and the Academy of Motion Picture Arts and Sciences, and these 
experiments were concluded just previous to the Hollywood meeting. 
The use of sound in conjunction with the motion picture was just be- 
ginning to be discussed, but with many misgivings. Our" Society 
staged the first demonstration of Photophone equipment in Holly- 
wood, but this attracted but slight attention from the producers. 
Six months later the sound revolution commenced. There was a 
mad scramble to build new stages and to modify old ones, and within 
a relatively short period of time there was an influx of a large army of 
skilled technicians to take care of the new equipment and procedure. 



In the short space of three years remarkable advances have been 
made in the technic of recording sound and in the making of motion 
pictures, and it is, therefore, fitting that we should hold a national 
meeting in this center of production in order to exchange ideas and 
to discuss our new problems and recent researches. 

But during these three years our Society has grown accordingly. 
For the benefit of those who are not well acquainted with our Society, 
it is a scientific organization patterned along the lines of many of 
the older scientific societies and serves as a stimulating, collecting, 
and coordinating medium for the technical and scientific knowledge 
appertaining to the motion picture industry. 

Our membership of about eight hundred, which is distributed 
among eighteen different countries throughout the world, is as 
diversified as the various arts and sciences which serve the industry 
and includes research scientists from the universities and industrial 
research laboratories and theaters, and executives from all branches of 
the industry. 

Eligibility for membership is determined by the Board of Govern- 
ors, which has interpreted the word "engineer" to apply to anyone who 
contributes to the building of a motion picture, so that those who con- 
tribute literary, dramatic, and artistic talent are equally as eligible as 
those who direct the business of production and exhibition of motion 

Membership is of four types: Associate, Active, Sustaining, and 
Honorary. Any one who is interested in motion pictures is eligible 
for Associate membership. Active membership is granted to those 
who have gained distinction in their particular field of endeavor. 
Sustaining members are those who contribute substantially to the 
support of the Society, while Honorary membership has been granted 
those scientists of international fame who, by their inventions and 
achievements, have been largely responsible for the building of this 

Conventions of our Society are held semi-annually and the various 
scientific papers and committee reports presented at the technical 
sessions, together with the discussions resulting therefrom, are pub- 
lished in the JOURNAL of the Society, issued monthly. In addition, 
the JOURNAL contains contributed papers, abstracts of current tech- 
nical literature, patent abstracts, translations of outstanding articles 
appearing in foreign technical publications, reports of committee 
activities, and book reviews. During the year 1930, 1,500 pages of 

Sept., 1931] BANQUET SPEECHES 419 

scientific data were published, including over 100 technical papers 
dealing with the various aspects of production and exhibition. 

The Society's Transactions, which were published quarterly from 
the year 1916 to 1929, together with the JOURNAL of the Society pub- 
lished since January, 1930, constitute the most comprehensive source 
of motion picture technical information in the world. The potential 
value of this knowledge to the industry is incalculable and the actual 
cost of the research work required to obtain it amounts to millions 
of dollars. The JOURNAL of the Society is distributed gratis to mem- 
bers but is available to non-members by subscription. 

The Society maintains local sections with headquarters in New 
York, Chicago, and Hollywood, which foster a spirit of cooperation 
among the members who cannot always attend the semi-annual 
conventions. The Hollywood section keeps the parent body in 
touch with activities on the West Coast and maintains contacts with 
the Academy of Motion Picture Arts and Sciences. 

It is through the medium of the committees that the Society best 
serves the industry in a cooperative and coordinating capacity. The 
bi-annual report of the Progress Committee gives, in condensed form, 
the essential technical developments in the fields of production, dis- 
tribution, and exhibition throughout the world. 

The Standards Committee has facilitated the interchange of the 
essential parts of apparatus throughout the industry and has pub- 
lished details of these in booklet form in collaboration with the Ameri- 
can Standards Association. The Society has also collaborated with 
the British, French, and German technical societies on matters relat- 
ing to standards. 

Other committees of the Society have dealt with progress in color, 
methods of securing better sound recording and reproduction, and 
improved methods of studio lighting, while the Historical Committee 
has prepared reports on the accomplishments of the industry's 
pioneers and is assembling historical apparatus which will be placed 
in a suitable depository. 

The subject of projection has been given special attention by the 
Projection Practice, Projection Theory, and Projection Screens Com- 
mittees and, as a result of their efforts, recommendations for standard 
layouts of projection rooms of various sizes have been made and data 
secured for formulating a tentative standard for screen brightness. 

The past year has also been conspicuous by virtue of increased ac- 
tivity of the Society in relation to collaboration with other organiza- 


tions and societies having interests related to our own. The Society 
has acquired membership in the American Standards Association 
which has recognized the various standards adopted by the Society, 
and also in the National Fire Protection Association which has in- 
vited the Society to collaborate with regard to safety measures in the 
handling of nitrocellulose film. Contacts have been made with the 
American Institute of Architects with a view to collaboration in 
the design of theaters, particularly with regard to projection and 
acoustical requirements. 

The Society will be officially represented at the 1931 International 
Congress of Photography in Dresden and arrangements for the 
exchange of technical manuscripts have been made with the Deutsche 
Kinotechnische Gesellschaft, which has also conferred Honorary 
membership upon the Presidency of our Society. 

The need for education in the fundamental principles of science 
as related to motion picture technology has also been recognized, 
and, as a result of encouragement by the S. M. P. E., the Massachu- 
setts Institute of Technology has laid out a special four-year course of 
instruction for those who wish to enter the technical phases of the 
motion picture industry. 

It has been suggested that possibly there is some duplication of 
effort on the part of the S. M. P. E. and the Academy. The Tech- 
nicians Branch of the Academy is likewise composed of scientists and 
technicians whose activities are devoted to education of the in- 
dustry's personnel, the publication of technical knowledge, the stand- 
ardization of practices, and the directing of cooperative research, 
but its interests to date have been focused largely on problems relat- 
ing to the application to the production of motion pictures of the 
tools which the engineer has devised; while the S. M. P. E. has been 
concerned, not only with the fundamental principles of science, but 
with the devising and making of the tools of the industry and with 
finding improved methods of their application. 

There is adequate room for all technical organizations in this great 
industry. One organization cannot give adequate attention to all 
the technical phases involved; and, on the other hand, the greatest 
benefit is often derived when two investigators tackle a problem inde- 
pendently they often see the problem from different angles, and 
their combined researches tend to constitute a more complete solution 
of the problem. However, we must cooperate closely and without 
rivalry. Each organization should draw attention to the publica- 

Sept., 1931] BANQUET SPEECHES 421 

tions of the other. The S. M. P. E. has paved the way by devoting a 
section of its JOURNAL to technical activities of the Academy. We 
shall be glad to circulate with our JOURNAL any information relating 
to publications of the Academy it is our duty to disseminate knowl- 
edge the matter as to when, or where, or how the knowledge origi- 
nated is immaterial. 

There must also be the closest cooperation between committees 
of the various technical organizations in the industry, especially 
those dealing with the standardization of practices. 

But how can you producers and your executives be of assistance 
to our Society? By taking an interest in technical matters by 
encouraging your men to keep posted on the latest technical develop- 
ments as published in our JOURNAL by urging them to attend con- 
ventions and sectional meetings, and to take an active part in the 
discussions and by allowing them to spend some portion of their 
working time in the interests of the Society. At these meetings they 
will make new friends and get new ideas. The importance of co- 
operation was never so great as at the present time. The day is gone 
when we can depend on the genius in the garret for discoveries 
nowadays they result from the combined efforts of many workers. 
The future of your business depends on your man power you owe it 
to your men to help educate them, and they, in turn, must sort out 
the information which can be applied to your own individual prob- 
lems. You can also help by taking out sustaining memberships in 
our Society. A thousand dollars spent in this way will be returned 
to you a hundred-fold by virtue of increased knowledge and elimina- 
tion of duplication of effort. 

I think no one will deny that the engineer is destined to play an 
increasingly important part in this great industry ; and the producer 
will have to depend to an increasing extent on the engineer to add 
novelty to his presentations. It is doubtful if there will be epoch- 
making engineering developments in the immediate future as revo- 
lutionary as the introduction of sound. The developments will 
probably be in the nature of improvements in quality both of black- 
and-white and colored pictures and of the sound, but these improve- 
ments will only be effected by paying the closest attention to minute 
details. There is hard work ahead. 

The quality of the sound as reproduced in conjunction with the 
motion picture must be improved if the public is to remain enter- 
tained. The reproduction of speech is very satisfactory, but that of 

422 BANQUET SPEECHES [j. s. M. P. E. 

music, as encountered in a very large proportion of theaters through- 
out the country, leaves much to be desired. There are serious leak- 
ages from the bucket of sound quality in the transfer from recorder 
to laboratory to projector to loud speaker and these must be 
reduced to a minimum. This can be accomplished only by research 
and education of personnel all along the line. 

If I were a producer, before participating in the threatened revival 
of musicals, I should pay a great deal of attention to the subject of 
projection. Most producers are likewise exhibitors and realize 
that it is foolish to spend millions on a production and have the 
artistry of the picture destroyed by imperfect projection. The pro- 
jectionist is one of the most important cogs in the complex motion 
picture mechanism, and he should be encouraged and educated. 

In order to reproduce sound with a more perfect degree of realism, 
we engineers must extend the frequency and volume range of the 
reproduced sound, reduce ground noise still further, and add sound 
perspective. Recent researches have shown that the sound energy 
produced from a symphonic orchestra of only moderate size may be 
as much as 50 watts during the louder passages, which would require 
from 100 to 200 watts of undistorted power from the amplifying 
apparatus. When we consider that many of the existing sound in- 
stallations are capable of handling only a maximum of 10 watts, it is 
realized that newer and more powerful equipment will eventually be 
required to give the public the degree of realism which it demands. 

I think that in the future, the industry can expect a continued 
series of technical developments from the engineer such as have char- 
acterized the past few years. The application of these will require 
increasing expenditures if entertainment is to be forthcoming which 
is better than that which the radio and the home movie can provide 
in the home. 

The theaters of the future must have larger projection rooms to 
accommodate the increasing amount of apparatus which will be 
necessary manned by men who will watch over its operation with 
the skill and care of a conductor directing an orchestra. Such equip- 
ment may include machines for reproducing sound from a separate 
film record with multiple sound tracks to permit of sound perspective 
and special effects with sound equipment having adequate reserve 
power to simulate every type of natural sounds and with project- 
ors capable of giving depth to the picture. Relief projection without 
the aid of auxiliary devices has recently been demonstrated, and these 

Sept., 1931] BANQUET SPEECHES 423 

experiments have revived the hope for the ultimate production of 
stereoscopic motion pictures. 

Before it is possible to televise motion pictures in the theater which 
will be as clearly defined as the present theater picture, it is apparent 
that some new fundamental scientific discovery will have to be made. 
Utilizing present principles, the entire commercial broadcasting 
channel would be required to obtain sufficiently critical definition. 

Color has not had a fair chance. I think that color inserts of pretty 
ladies are more fully appreciated, at least by the male public, than 
statistics would indicate. The sudden demand and the rush to obtain 
color prints without sufficient time for preparation made it difficult 
to get prints of satisfying quality. The complaint that some colored 
motion pictures have caused eye-strain was undoubtedly a result of 
the fuzziness of the pictures. The eye did not know whether the 
picture or itself was at fault and became all tired out trying to bring 
the picture in focus. This difficulty of securing colored pictures 
which are equally sharp as the black-and-white ones has now been 
practically overcome. 

Much research is in progress on color work, and an ultimate solu- 
tion is assured. 

Investigations by the Standards Committee of the S. M, P. E. 
have shown that an extremely wide film is not necessary to produce a 
large screen picture. So far as can be predicted, a film 50 mm. wide 
is adequate for even the largest theaters; and, with only moderate 
improvements in film emulsions with respect to graininess, the 
present 35 mm. film would be adequate for the largest pictures pos- 
sible in the average theater, especially if the picture and sound records 
were placed on separate films. 

But these improvements will be accomplished only as a result of 
continued research on the part of many workers. Research work 
may be of two kinds investigations in pure science or the unfolding 
of the secrets of nature, and industrial research, or the application of 
known fundamental principles to industrial practice. For example, 
the discovery by pure research that a hot body gives off particles of 
electricity and that light drives out particles of electricity from mate- 
rials, was utilized by virtue of applied research to the development 
of vacuum tubes and photoelectric cells, which are the keystones 
of our modern sound recording and reproducing equipment. 

To date the industry has put on the manufacturer the bulk of the 
burden of developing the science which it is applying, but the success- 


ful producer of the future will contribute his fair share in order to 
insure an adequate supply of new entertaining media. But how can 
this be accomplished? It is not feasible for the S. M. P. E. or the 
Academy to establish a research laboratory, but they can help stimu- 
late research and contribute toward the establishment of research 
fellowships in the various universities throughout the country. As a 
result of negotiations with the Massachusetts Institute of Tech- 
nology and the School of Optics of the University of Rochester by 
our Society, I am authorized to state that these universities will, 
if the necessary funds are forthcoming, establish fellowships for the 
investigation of problems appertaining to the motion picture industry. 
I have in mind such problems as the effect of viewing motion pictures 
on eye fatigue and the merits of non-intermittent projection, which 
can only be conducted successfully by the collaboration of a large 
number of individuals. I know of no more valuable contribution 
which you can make for the welfare of the industry. 

In conclusion, may I remind my co-workers of a tribute paid to the 
engineer from this platform three years ago by the late Milton Sills on 
the occasion of the banquet tendered our Society by the Academy. 
These were his words: "If I had my life to live over again, I should 
not elect to be an actor, but a scientific research worker. We actors 
get our names in electric lights, but we are soon forgotten and pass 
into oblivion. You scientists are making contributions of lasting 
value and are therefore giving one of the greatest services to the hu- 
man race." 

My first introduction is to one of our technical members whose 
researches have been largely responsible for the vacuum tube which is 
used in our sound recording and reproducing apparatus Dr. Lee 
de Forest. 

DR. DE FOREST : Chairman, guests, those who enjoy the Society of 
Motion Picture Engineers, and Motion Picture Engineers : it is a great 
pleasure to be here in Hollywood, and to greet the Convention as a 
resident. I am reminded as I sit here tonight of what happened 
10 years ago this month, for I have here by my side the first talking 
motion picture cameraman and sound recorder, William Garrity. 
It was 10 years ago that Garrity recorded sound on picture film for 
the first time in America. That was in my laboratory in New York 
City. Microphones were not much in those days. On that occasion 
the small microphone used was concealed beneath Mr. Garrity 's 
vest while he posed before the camera. The recording was what you 

Sept., 1931] BANQUET SPEECHES 425 

can well imagine it was. Mr. Garrity is now engaged in the very 
interesting work of recording the Disney cartoon films instead of 
trying to record the voice of human action. And had we contented 
ourselves at that time with the recording of the more or less imaginary 
sound of cartoons, we might have succeeded much more rapidly than 
we did. For those first recordings were much like those sounds 
which Mickey Mouse makes from the screen today. I know that we 
have a long program and I do not want to take up more time. I want 
to congratulate our President on his most enlightening discussion of 
the present state of this art. It was most interesting. 

My position out here makes me think of the traveling salesman 
representing the Scottish mercantile firm, who was shipwrecked on 
the Hebrides Islands, and who sent a telegram to his home office 
asking instructions. They replied, collect, "Your summer vacation 
began as of yesterday." I feel, while I am out here enjoying the de- 
lights of watching what my successors are doing in this art, very much 
like that salesman, only shipwrecked on a South Sea Island. I am 
having a delightful time keeping in touch with the rapid strides, the 
impressive improvements which you motion picture engineers are 
making in Hollywood, and I am glad to know you all. 

MR. FRANK WOODS : I was very much impressed by the statement 
made by your President of what the engineers have accomplished 
and some of the things that they hope to accomplish. My memory 
of this business goes back to the time when the engineer was unknown. 
The technical man was not even referred to in those terms. The 
technicians of those days the earliest days of pictures consisted 
of the cameraman, possibly a "prop" man, and the laboratory 
men. The art department was a painter who painted on canvas 
drops and sides. He sometimes painted an audience on the back of 
the canvas. In the picture Ben Hur, the first time it was made in 
1907, the audience was painted on a back drop and when the wind 
blew the curtain, you really had a moving picture the audience 
moved. The actor was afraid to work in motion pictures under his 
own name, so he would apply for the job of "posing" under a fictitious 
name. Some of those fictitious names became well known in pictures 
afterward. The director directed his pictures from what were called 
suggestions. There were no writers in motion pictures. If one 
wanted to sell an idea to a company, he would sell a suggestion. 
When I entered the business, the price of a suggestion was fifteen 
dollars. Some of the companies paid only five dollars. The author 

4'2(\ BANQUET SPEECHES [j. s. M. P. E. 

was only known to the picture business as the person from whom we 
stole a story. It is a long way from that time to this twenty-three 
or twenty-four years not so long in time, but very long in things 
that have been accomplished. For example, the technicians have 
now become engineers. I think the word itself has an impressive 
sound to the producers. Engineers are now recognized by the pro- 
ducers as a class of people on whom they have to depend and to whom 
they cannot dictate, because as a rule they do not know what the 
engineer is talking about. The writer he should really be called an 
author has not yet arrived at that position, but he is improving in 
his standing. Through the Academy the screen authors of the pres- 
ent time are now preparing to negotiate an understanding by which 
they hope to achieve a greater freedom of authorship, all of which is 
meant to bring about better motion pictures. For this improved 
standing the screen authors must thank the engineers because it is 
due to the achievements of the engineers that the writers are now 
being better recognized and can lay claim to genuine authorship. 
When the engineers gave us the talking picture, it became more and 
more necessary that complete scripts including dialog should be 
written scripts that could not be tampered with after having been 
composed. Hence the author owes to the motion picture engineers a 
great debt of gratitude. 

MR. CLINTON WUNDER: President Crabtree, Mr. Chairman, 
friends of the Academy and of the Society: I am in a difficult spot 
because on one side of me is a granddaddy of the Academy, who was 
present at its birth and fed it from a bottle and nursed it through 
infancy, and on the other side of me is Mr. Crabtree who speaks a 
technical language about which I profess to know little. My duty 
remains to represent the Academy. 

Twelve years ago, I made my first speech on motion pictures in 
New York City. At that time, there were seventeen speakers on the 
program. Tonight history is repeating itself for there are fifteen 
speakers on this program, which suggests to me that brevity is in 

The combined technical and scientific intelligence of those who 
make up the ranks of the Society of Motion Picture Engineers and the 
Academy of Motion Picture Arts and Sciences have projected the 
human voice in a mighty volume which everyday rings out in twenty- 
seven languages into the ears of peoples of every community in 
the world where electricity can be had. A weekly world audience 

Sept., 1931] BANQUET SPEECHES 427 

,of 250 million people (white, yellow, and black) hear what you 

When silent pictures decided they wanted to speak, you gentlemen 
helped to teach them how. The speed with which they gained this 
vocabulary, the clearness of their pronunciation, the success of 
their words, they owe to you. Nor is entertainment the only product 
of your scientific achievements. The little red schoolhouse, the 
church, the university, and the great convention auditoriums now 
ring with the messages of education, the words of leaders of social 
thought, and the voice of great statesmen. The news weekly has 
become a news agency of vivid information and interest since sound 
came in. The comic cartoon has chased our gloom away to the tune- 
ful antics of cows, goats, mice, and cats. The voice of the greatest 
clergyman is now heard in the smallest rural church accompanied 
by the choruses of trained singers which hitherto only the wealthiest 
congregation could listen to. 

Therefore, not only Hollywood welcomes you today, but the people 
of two continents welcome you. They watch with interest that which 
you will say and do throughout your convention program. They 
will expect ever-continuing improvement of this vehicle you have 
taught them to enjoy. The Society and the Academy have much in 
common. Many belong to both the Society and the Academy. We 
benefit from the discoveries and the researches made by each other. 
Gains are placed together in the same treasury. Your interests and 
ours are the same. Your service and ours are interrelated. 

The manufacturer of film, the equipment companies, the actor, 
writer, director, the sound engineer and technician, the cameraman, 
and the producers are of necessity partners. Into this partnership 
the public has come, by buying stocks in our companies and by plac- 
ing money in the box-office. I am sure I speak for the entire Academy 
membership when I express the sincere hope that the acoustical prop- 
erties of your convention hall's walls will be great enough to challenge 
anew the attention of that world audience which demands from us our 
best in supplying a never-ending program of films of quality to be 
seen, to be heard, to be enjoyed. 

MR. FRED PELTON: Mr. Chairman, artists, and the Society of 
Motion Picture Engineers: there is a cloud over the industry at 
the moment. Three years ago we had not a gathering such as this, 
but a group of gatherings at the Biltmore Hotel, and at that tune 
technicians of the industry contributed very greatly to reducing the 


cost of making motion pictures and there was a general stimulation 
of technical activity. There is one problem which the S. M. P. E. 
can solve ; and that is the problem of the silent motion picture camera. 
The cumbersome camera housing which we use today is a great con- 
sumer of time, and undoubtedly adds to the cost of making motion 
pictures. I understand that there are two manufacturer members of 
the Society who are producing silent movement motion picture 
cameras very little heavier than the old silent camera. One impor- 
tant thing for the Society of Motion Picture Engineers to do is to ex- 
pedite the silent camera and get it into the industry as quickly as 
possible. This will help to dispel the cloud. 

MR. CAREY WILSON: Mr Chairman, and Ladies and Gentlemen : I 
have been waiting for just three years since your last convention 
here to get even with you guys. Three years ago I walked in- 
nocently into something which certainly appears to have had impor- 
tant consequences. Mr. Woods, of the Academy of Motion Picture 
Arts and Sciences, asked me then if I would attend the convention 
of the S. M. P. E., and read a paper. So I prepared a harmless little 
paper and read it, and was making a graceful exit to mild applause 
when the chairman called me back and advised me that all speakers 
were required to take the rostrum and answer questions. Rather 
helplessly I "did so. We started out with such questions as "What 
is a scenario?" and I answered, of course, that I didn't know. 
We graduated in a few minutes to such more leading questions 
as, "How much money does Jack Gilbert really get every week?" 
And a little later we got into such serious problems as the desire to 
know Greta Garbo's telephone number. One of the questions that 
turned out rather badly, I'm afraid, and that started a lot of trouble 
was the question, "W T hat can the engineer do to help the writer?" 
That was a tough one. Rather foolishly I said off-hand: 

"I think the only way is for the engineer to give the writer new 
machinery, so that the writer will have a broader scope and a wider 
field in which to exercise his talents." 

Well, gentlemen, one of you guys went home to his laboratory, 
picked up some pieces of wire, an old telephone transmitter, and went 
to work. Three weeks later we had talking pictures. Six months 
later half the people in Hollywood were out of work, and the other 
half didn't know anything about talking pictures, either. 

I will never ask for any more help from the engineers. 

I might say to all of you, and particularly to Doctor Mees, to please 

Sept., 1931] BANQUET SPEECHES 429 

have a heart and don't go inventing anything new for a little while, 
until we get caught up. 

You gentlemen have certainly improved matters marvelously since 
the introduction of sound pictures. When talking pictures first 
came in, I monkeyed with the idea in a rather obscure studio. The 
first time I went on a sound stage, I discovered the problems were 
many : we had a microphone somewhat resembling a sewing-machine 
suspended from the ceiling ; you had to group your actors around that 
microphone until they looked like a Notre Dame huddle; but the 
poor cameraman was in a worse spot. The sound stage of the early 
days resembled the home factory of that famous character created by 
Chic Sale. 

Then, when I went to see the picture, it happened to be running 
in a small house. Gentlemen, that house reminded me of the City 
Hall Auditorium in the small town where I once put on a high-school 
show. I asked the man who ran the auditorium: 

"How are the acoustics?" 

He said, "We ain't got no acoustics." 

In the early days of sound pictures you sat and listened to your 
picture and wondered who it was that had translated your dialog into 

I don't suppose any of you folks realize the chaos that resulted in 
our industry here with the introduction of talking pictures. I can 
tell you a story about a director who was a practical joker, which 
may illustrate our confusion and ignorance of sound. This director, 
Micky Neilan, asked an actor friend to make a sound test. The actor, 
who happened to have a very deep voice, came on the set and spoke 
certain lines in the test. When he left, Micky got his young girl 
secretary to speak those same lines on a separate sound track. When 
the actor came back several days later to hear his test, Micky ran 
the actor's photograph film synchronized with the secretary's sound 
track. When the lights flashed up in the projection room, the actor 

"My God, Micky, I was afraid I wouldn't record well, but I didn't 
think I'd turn out to be a damned soprano." 

I am sure, gentlemen, improvements will have to go on from this 
day as they have from the pioneer days of sound. To show my 
respect for your abilities, I can only say that I hope we here will 
progress as well as I know you engineers will. 

CHAIRMAN: We have with us a guest who came all the way from 


Germany, and who is a member of our Society and of the Deutsche 
Kinotechnische Gesellschaft. Perhaps he may have a few words to 
say to us. 

MR. HANS BOHM: I would like to express my appreciation at 
being able to attend this wonderful meeting of the Society in Holly- 
wood. All my German fellow friends of the Deutsche Kinotech- 
nische Gesellschaft, which is very much honored to have your 
President as its honorary member, envied me as I left for my visit to 
America; and I feel sure that they will envy me even more when I 
return and tell them of all that I have seen and heard over here in 
this marvelous country of progress, research, and science. 




The last report on the work of this committee was presented to the 
Society at the New York meeting in October and appeared in the 
December, 1930, issue of the JOURNAL. The present report is concerned 
chiefly with the activities of a subcommittee consisting of Messrs. 
Batsel, Chairman, Evans, Griffin, La Porte, Shea, Spence, and Spon- 
able, which was appointed to study the wide-film situation. The 
recommendations of this subcommittee (wide film) have been con- 
sidered and approved by a majority of the Standards Committee, 
either at the meeting held in New York on May 2nd or by 

The problem of a satisfactory wide-film layout has been under 
consideration by this committee for some time, and previous reports 
have discussed its many obvious advantages and its economic limita- 
tions, due in part to the existence of a large amount of 35 mm. equip- 
ment. This committee has felt that the adoption of release prints 
having a width of 65 or 70 mm. is economically impractical and has, 
therefore, been working for some time on an intermediate film size 
that would have most of the advantages of the wider film but that 
could be used interchangeably with 35 mm. film in existing projectors 
afte*r suitable alterations. As indicated in our last report, the ratio 
of picture width to height is constrained by the balcony cut-off and 
proscenium arch in existing theaters to be in the neighborhood of 1.8 
to 1 . The combination of a picture of these proportions, the feature 
of interchangeability with 35 mm. films, and provision for a sound- 
track of adequate width with suitable margins leads to a film ap- 
proximately 50 mm. wide. 

A tentative layout for a 50 mm. release print had been drawn up at 

*Presented at the Spring, 1931, Meeting at Hollywood, Calif. 



[J. S. M. P. E. 



:- FULL S/Z 

- IIO 

. no 

FIG. 1. Layout for 50 mm. unshrunk 
release print. 

FIG. 2. Layout for 50 mm. unshrunk 


the time our last report was presented but it was not included with the 
report because the committee had had no opportunity of putting it to 
a practical test. Through the unstinted cooperation of Mr. Sponable 
and others, equipment for taking, processing, and projecting this 
film has since been made available to the subcommittee so that 
actual tests of the suitability of the new film could be made. It 
is the unanimous opinion of this committee that the new film 
has all the important advantages of the 65 or 70 mm. film, and 
that, due to its narrower width, all the major difficulties involved 
in handling the wider films have been eliminated. We are includ- 
ing in this report the layout drawn up by the subcommittee for a 
50 mm. (unshrunk) release print (Fig. 1) and a 50 mm. (unshrunk) 
negative (Fig. 2.). 

We wish to make it clear that, due to the present lack of interest 
in wide film on the part of the producers, we are not asking the Society 
for formal approval of the 50 mm. film dimensions at the present time. 
We are, however, publishing this report as a matter of record, so that 
when and if the industry desires to make use of the superior results 
achieved with the wider film, the results of this work will be available. 
It is contemplated that, if sufficient interest becomes apparent, a 
demonstration of the new film before the Society can be arranged at 
some subsequent meeting. 


A subcommittee on nomenclature under the chairmanship of Mr. 
Rayton has prepared a careful revision of the glossary of motion pic- 
ture terms that appeared in No. 37 of the Transactions of the Society. 
A large amount of work has been done on this project to bring the 
definitions into line whenever possible with those already adopted 
by other societies such as the Institute of Radio Engineers, the Ameri- 
can Institute of Electrical Engineers, the Optical Society of America, 
the Illuminating Engineering Society, and the Academy of Motion 
Picture Arts and Sciences. Mr. Rayton's subcommittee has been 
very ably assisted in this work by Messrs. R. E. Farnham, Clifton 
Tuttle, T. E. Shea, and Sylvan Harris (editor-manager). The glos- 
sary will appear in an early issue of the JOURNAL. 


The subcommittee on standard practice under the chairmanship 
of Mr. Rackett has carried forward the program previously outlined 

434 STANDARDS COMMITTEE [j. s. M. p. E. 

(/. Sac. Mot. Pict. Eng., XV (Dec., 1930), p. 818.) but has no formal 
report to make at this time. 

A. C. HARDY, CJiairman 












MR. DUBRAY: To all appearances, the size and shape of the perforations as 
recommended offer dimensions suitable for 50 mm. film which would prove 
adequate, especially considering that the rectangular perforation is recommended 
for both negative and positive. 

I have been in Hollywood for the last six months and have conducted a per- 
sonal investigation from which it appears that the ratio 1 to 1.8 for the motion 
picture image is not in accordance with the apparent needs of the artistic workers 
in the motion picture field. Cameramen, directors, art directors, etc., object 
quite strenuously to such an elongated form of the screen, contending that it is 
not adequate for the proper pictorial presentation of the great majority of motion 
picture scenes. 

The Committee has been, in my estimation, considering a maximum width 
necessary to fill the proscenium, and has suggested a height suitable to the 
geometry of the auditorium. However, I do not believe that it is essential to 
cover the entire width of the proscenium, and it appears that a ratio of approxi- 
mately 3 to 5 better answers the requirements of the artistic workers of our 

I would like to suggest that very close collaboration with the American Society 
of Cinematographers and the Academy of Motion Picture Arts and Sciences 
would be highly desirable in order to arrive at a better understanding than we 
have today. 

MR. BATSEL: In deciding upon the 1.8 to 1 ratio, consideration was given 
not only to the dimensions of the theater stage openings, but also to the ratio 
which would permit the picture to be viewed without allowing the edges of the 
picture to intrude upon the viewer's consciousness. Everyone will agree that 
with the present dimensions of the picture, one is always more conscious of the 
sides than of the top and bottom. When viewing the 2 to 1 picture, one is con- 
scious of looking through a window which is too wide. These pictures were 


viewed under various conditions, and appear to be very easy to look at without 
being overly conscious of the sides or top, although the ratio is not the whirling 
square ratio which the artist likes. I think that it most fully meets the require- 
ments of the theaters and at the same time gives one a wider angle of view than 
the 1.6 to 1 ratio. The dimensions of the perforations were debated for many 
hours. I cannot begin to repeat the arguments that were given for wider per- 
forations or for the standard perforations. But after many meetings, every- 
body who attended was convinced that the recommended perforation would be 
satisfactory. Mr. La Porte has done considerable work with this film. Mr. 
Sponable has had experience with 70 mm. film and has tested the 50 mm. film 
with standard perforations. Others have run many 63 and 65 mm. film with 
the same perforations, and all the data we could accumulate indicated that it 
would be perfectly satisfactory. 

MR. GRIFFIN: For the sake of argument, we might all agree with the artists 
in so far as their opinions on the size of the picture are concerned. However, the 
artists and the directors are not dealing with the theater. They are dealing 
with the artistry of the picture, and are doing a good job. However, a very 
comprehensive survey was made which definitely indicated that pictures of dimen- 
sions other than those which have been submitted would in the majority of cases 
be impracticable. The proscenium arch and the balcony height, and all the 
things to be considered when changing the size of the picture, must be very 
carefully considered before standardizing on a definite size of picture. 

PRESIDENT CRABTREE: Should we not establish what is the best proportion 
and in the future design theaters accordingly? 

MR. GRIFFIN: That would be an ideal procedure, but there are already 
22,000 theaters in the country into which we may have to put the new picture, 
and it would not be well to standardize on any size that would not be suitable 
for all these houses. 

MR. SCHLANGER: The proscenium arches are made of metal lath and can be 
altered to accommodate the right size picture, and the balcony seating arrange- 
ment can be changed as well. 

MR. GRIFFIN: That may be true in many instances, but consider this pros- 
cenium. It would be a difficult matter to move it without going to the outside 
of the building; and such a condition exists in the majority of theaters not con- 
structed along the lines of the de luxe houses. It is not a matter of height, but 
of width, and if we extend the picture to the side walls of the theater it would 
be a rather poor thing to look at. It must be framed according to the size of 
the theater in which it is being presented. 

MR. DUBRAY: I agree with some of Mr. Griffin's statements, but I am afraid 
that my statements have been misunderstood. I do not intend to suggest that 
a screen having a 3 to 5 ratio should fill the total width of the proscenium. This 
would, of course, not permit people sitting at the rear of the auditorium to see 
the entire height of the picture. 

What I intended to say was that a maximum possible height should be de- 
termined, letting the width of the screen take care of itself in the proportion of 
3 for the height to 5 for the width. 

MR. GRIFFIN: While the 3 to 5 ratio may be artistically good, it is still open 
to the objections I have already stated. But there is another consideration 


\\ r arc talking in terms of wide film; and I have seen pictures of various ratios 
projected, including that suggested by Mr. Dubray, and those approximating 
that ratio seem only to be glorified 35 mm. pictures. They do not give the 
effect which we all seem to be after the so-called wide picture. Mr. Dubray 
has not seen actual samples of film made by the Committee for our use. They 
an- really beautiful, and as Mr. Batsel said, are very easy to look at. 

MR. SCHLANGER: As far as the structure of the building is concerned, I agree 
that one must sacrifice width for size of structure. However, there may be simul- 
taneous actions occurring on both sides of the picture, and if the film is too wide 
it may be difficult to connect both actions with the proper vertical accent which 
affects good picture positions. 

PRESIDENT CRABTREE: Mr. Hardy emphasized the importance of the 
interchangeability of the mechanism for use with 35 mm. film. What saving 
would that involve that is, what is the difference in price between such a com- 
bination machine and a new machine to handle the 50 mm. exclusively? One 
would assume, of course, that the 35 mm. film would be retained until the in- 
dustry is ready to switch to the 50 mm. type. 

MR. GRIFFIN: In order to introduce wide film at all it would have to be 
introduced in a very economical way. Two sets of equipment cannot be installed 
in any projection room; certainly not in 90 per cent of the theaters. That means 
that it would be impossible to introduce wide film to any large extent with the 
existing 35 mm. equipment installed. The problem, then, is to make equip- 
ment that can be changed within a few seconds so that either 35 mm. or 50 mm. 
film can be mn on the same equipment. The cost of building 50 mm. equip- 
ment would not be much greater than the cost of building the present equipment, 
but it would not have the interchangeable feature. It so happens that 50 mm. 
film can be readily installed in any of the theaters with the existing type of 
equipment at a very nominal cost. I cannot give the price because that data 
is not available. 

PRESIDENT CRABTREE: Could you outline exactly what has to be done to 
change over the machine? 

MR. GRIFFIN: The same intermittent movement, the same shafts, and the 
same gear ratios are used as in the 35 mm. equipment, but the sprocket struc- 
ture is simply lengthened out so that one end of the sprocket may be pushed 
in for 35 mm. film and pulled out for 50 mm. film. The second change is 
to pull out the 35 mm. aperture and substitute a 50 mm. aperture and guide for 
the 50 mm. film. The only other change necessary is to replace the gate which 
can be done in a few seconds. The same procedure applies to any sound equip- 
ment, and the magazines must be widened by using a new door. These features 
are very inexpensive as compared with the cost of new equipment specially built 
for one size of film. 

PRESIDENT CRABTREE: Will such sprockets get out of alignment and perhaps 
damage the film? 

MR. GRIFFIN: Not with the construction under consideration. The feed 
sprocket and hold-back sprocket are easily changed, and only a relative amount 
of accuracy is required; but greater accuracy is necessary in the case of the 
intermittent sprocket. The problem is far from being insurmountable. 

PRESIDENT CRABTREE: I would like to suggest to the Chairman of the Com- 


mittee that in order to enable the members who did not have the opportunity 
to attend this meeting and to hear all these intimate discussions to vote intelli- 
gently, the report might be somewhat elaborated, including a few of these reasons 
why the Committee has arrived at this decision. 

MR. JONES: It seems to me that the Committee has proposed a very definite 
disposal of this report. As Mr. Hardy points out, the Committee is not pro- 
posing a standard to be adopted by the Society at present, but has presented 
the conclusions it has reached up to the present time. If I understand correctly, 
the Committee proposes to let the matter rest in this state until such time as it 
seems expedient for the Society to take a definite action and I think Mr. Hardy, 
after this discussion, will present further facts for the adoption of this matter. 
Our course is to accept the report of the Committee and to do with the report 
just what the Committee asks us to do. This is a tentative recommendation. 

MR. SHEA: It is greatly to be hoped that at the next convention Mr. Sponable 
will be able to give a demonstration with his apparatus such as he gave to the 
members of the Standards Committee, and it is also to be hoped that Mr. Griffin 
will describe his projector. Until this shall have been done, discussion of details 
seems ineffective. 

MR. GRIFFIN: The equipment will be available at the next convention if it 
is desired. The wide film program was started by one manufacturer and did 
not meet with the approval of other producers. We do not want to force the 
matter of standardization but we do want the producers to study the matter 
carefully and come to their own conclusions. 


The Projection Screens Committee commenced its operations in 
March. The first meeting was held on April 16th in New York, 
N. Y., at which the Chairman submitted a preliminary outline of 
the work proposed for the Committee to undertake. This outline 
was discussed and elaborated and as a result a second and more de- 
tailed outline was prepared and distributed among the members. 
The second meeting was held on May 14th. This preliminary report 
is based largely on material submitted and examined at that time. 

The main lines of endeavor are outlined as follows: Manufacture 
of Screens, Mechanics, Light Reflection Properties, Sound Trans- 
mission, Illumination, and Rear Projection Screens. Responsi- 
bility for the different sections has been assumed by the members 
with regard to their familiarity with the different fields. Con- 
siderable data will be collected on light reflection properties, bright- 
ness values of screens in theaters, and manufacture, installation, 
and maintenance of screens. It is also hoped that the Committee will 
be able to make recommendations as to the type of screen to employ 
under specified conditions of use. 


The following is in the nature of a preliminary report and, there- 
fore, is not as complete and conclusive as we should like it to be. 
Nevertheless, it is our opinion that it offers material which the So- 
ciety may find of interest at the present time and will indicate what 
may be looked for in our later report. 


Bases. The manufacture of sound screens is a critical under- 
taking in which all details must be given due consideration in order 
that uniformity and high quality of finished product may result. 
Most screens employ a fabric as a base although there are some 
which employ a metal. Essentially, the purpose of the fabric is 
to provide the necessary strength for the screen and to serve as a 
carrier for the light reflecting surface. Quite often the fabric is 
coated with a cellulose compound and the combination employed 
as a base. With some screens a slight translucency of the fiber from 
which the fabric is woven is desired. This is the case when the rear 
surface of the screen is colored in an attempt to impart to the 
reflected light a slight tone of the particular color used. It is more 
customary, however, to make the fabric as nearly white and opaque 
as possible in order to improve its light reflecting qualities. 

Surface Treatment. The base fabrics are treated in various ways 
to give various reflection characteristics to the screens. The 
surfaces are classified as matte or diffusing, beaded, or metallic, 
the latter two being somewhat directional in their distribution of 
illumination. They may be applied by a knife spreader process, 
by printing with rollers, or by spraying or painting. Great care 
must be taken to secure a uniform and sufficient thickness of 
coating to provide good light reflection characteristics while staying 
within the limits imposed by other conditions. As yet, no de- 
tailed information has been collected in regard to the materials 
which are commonly used for surfacing. 

It is present practice to color the backs of screens for purposes of 
identification. As mentioned before, however, color is sometimes 
used with thin surface layers to provide a slightly selective reflec- 
tion characteristic. 

Materials for coating vary greatly in their properties. Some 
diffusing screens are slightly glossy and others have perfectly flat 
white surfaces. Flat white seems best for avoiding surface glare and 
undesirable reflection at the seams. Diffusing surfaces may be hard 


or soft, smooth or rough. A hard smooth surface without sheen is 
apparently desirable since it is less apt to collect dirt and is easier to 
clean. Beaded screens require ingredients to hold the beads firmly 
in place. Most surfaces are formed from pigments and gums, oils, 
or other binders. In general, the gums and oils cause screens to 
become yellow with age. 

Fireproofing. At various times there has been agitation in re- 
gard to fireproofing of screens. This situation grew out of the prac- 
tice of using highly inflammable nitrocellulose bases. Screens of 
this type are undoubtedly fire hazards and their use has been 
largely discontinued. At present, practically all screens are either 
slow-burning or fire-resistant. They are made so by properly se- 
lecting the materials and by flame-proofing the base fabric prior 
to treatment of the surface. This Committee has found that it 
is impossible to successfully fireproof a screen after manufacture or 
when in place in the theater. It must be remembered that the screen 
is a small item in the stage equipment of a theater, that it is usually 
much less inflammable than the surrounding draperies, and that 
usually it is hung vertically and stretched tight, so that it is not 
likely to be the cause of fire. We know of no case in which slow- 
burning or fire-resistant screens have caused fires. In general, it 
devolves upon the exhibitor to make his choice of screens, depend- 
ing on his own local ordinances and conditions. The Committee 
is considering a recommendation relative to the marking of all 
screens which have been flame-proofed so that difficulties arising in 
this connection may be eliminated. 

Sound Requirements. After many tests, the necessary require- 
ments as to the ratio of open to solid space in sound screens have 
been determined by producers of sound equipment, and screen manu- 
facturers have guided themselves accordingly. Screens of the per- 
forated type in present use have a ratio of open to solid space of ap- 
proximately 8 per cent; screens of the porous type have a rather 
larger ratio. Acoustic theory indicates a minimum of 5 per cent 
as desirable. Perforations generally are made after the screen is 

Seams. In assembling screens the seams should be placed 
vertically. Care must be taken not to stretch the screens too 
tightly. Butt joints are used with some metallic and beaded 
screens employing cellulose coated fabric as the base but are not 
generally used with others. 



Size. The distance between the front row of seats and the screen is 
one determining factor for the size. The larger the picture, the more 
plainly imperfections in the film, such as graininess, .show up. This 
is very noticeable and objectionable in the nearer seats. Also, 
since the eye can satisfactorily accommodate itself to movement 
throughout a 60-degree angle, the distance between the front row 
and the screen should approximate 0.87 foot for each foot of screen 
width. For a 15-foot picture, a distance of at least 13 feet should 
therefore be provided. 

The size of picture should be determined by its distance from the 
rear seats. The width of the screen should be equal to approxi- 
mately one-sixth the distance from the screen to the rear seats. For 
a distance of 120 feet, therefore, a 20-foot picture should be used, 
provided there are no seats nearer the screen than 17 feet and the 
projection angle is not very great. These rules are intended only 
as guides. 

The standardization of sizes is of primary importance to both 
manufacturer and exhibitor. Many errors are made in ordering 
screens because of confusion in description, resulting in considerable 
monetary loss. Sizes have already been standardized by several 
manufacturers and large users, but not always in the same way. 
The Committee is considering for recommendation a set of dimen- 
sions to be used as standards and sub-standards. 

Mounting. Each manufacturer should determine the best method 
for mounting his own screens and advise purchasers accordingly. 
By taking proper care in mounting the screens, damage and cost of 
installation can be reduced considerably. A survey of instructions 
sent by manufacturers may lead to general rules. These may be 
drawn up into a revised instruction sheet for consideration by 

Masking. The usual masking is black. This results in a very 
marked frame which reduces the effect of "jumping" of the pic- 
ture caused by the film or projecting equipment. It has been felt 
that the resulting contrast is too great and various persons have 
advocated an intermediate gray. We are considering a suggestion 
that the mask be graded from black to lighter grays with the black 
edge next to the picture. 

Deterioration. All screens deteriorate with age: "silver" screens 
tarnish, other types become yellow. Yellowing of the surface is 


accompanied by a reduction in reflection value and by an undesirable 
color tone which is imparted to the picture. Yellowing is usually 
caused by gums and binders and not by the pigments. We are in- 
formed that of late there has been marked improvement in this respect. 

In addition to discoloring screen, accumulated dirt also causes a 
deterioration of reflecting qualities. The amount of dirt collected 
depends on the condition of the air in the theater, the precautions 
used to protect the screen, and the nature of its surface. It is 
essential that draperies surrounding the screen be cleaned regularly 
and that circulation of air through the openings of the screen be 
prevented. If possible, it should be enclosed when not in service, 
even though with the cheapest kind of material. The average 
useful life of a sound screen varies from one to two years, depend- 
ing on the conditions of use. 

Cleaning. Even with these safeguards the screen will gather dirt. 
An examination will indicate whether the dirt is dry or oily and, 
therefore, whether the screen may be brushed or not. If brushing 
is permissible, a long handled special brush should be obtained and 
the screen brushed once a week. It is also helpful to use a vacuum 
cleaner on the rear surface. More thorough cleaning should be done 
by experts who have sufficient scientific knowledge of screen materials 
to devise safe and suitable methods. Furthermore, certain types of 
screen cannot be cleaned satisfactorily at all. Each manufacturer 
should advise the users of his screens as to the possibilities. 

Reprocessing. Renewing of the surface of diffusing screens by 
spraying is receiving considerable attention. When carefully done 
and when the proper materials are used, completely satisfactory re- 
sults seem to be attainable. The spraying pigment should be highly 
reflecting, should not fill up perforations, and should not become 
yellow with age. The screen and surroundings should be thoroughly 
cleaned before the processing is undertaken. Such a renewal of the 
surface is not feasible on all types of screens. 


Total Reflection Factor. There are several ways of defining the 
total reflection factor, based on the methods of test used in different 
laboratories. The laboratory which makes most of the commercial 
measurements of screen reflection characteristics employs a method 
in which the light is incident on the test sample from all directions 
within a cone of 180 degrees. The angle of observation is 12 de- 



grees from the normal, and the light returned in this direction is 
taken to indicate the total reflection factor. The Committee ad- 
vocates the adoption of this definition as standard. 

Angular Distribution. One of the most important attributes of 
a screen is its ability to reflect the incident light to the observers. 
Angular distribution curves in the past have been obtained with 
light at normal incidence. Data collected by this Committee show 
that the average projection angle is approximately 15 degrees, 
measured to the perpendicular to the screen. Therefore, we believe 
that measurements with light incident on the test sample 15 degrees 
above the normal will give information more in keeping with condi- 
tions of actual practice. The reflected light would be measured in 


FIG. 1. Distribution of brightness in horizontal plane for diffusing screen. 

a horizontal plane and in a vertical plane containing the light 
beam, both normal to the screen sample. A more complete dis- 
cussion of this question will appear in our later report. 

The accompanying curves, Figs. 1-6, illustrate the variation in 
distribution of light at three angles of incidence, 0, 15, and 30 de- 
grees from the normal. It will be noted that with a smooth dif- 
fusing type of screen the difference beween measurements at zero 
and the other angles is appreciable but that the distribution is re- 
latively uniform. In the horizontal plane, there is considerable 
diminution of reflected light and some equalization in distribution 

Sept., 1931] 



for both beaded and metallic types. In the vertical plane for a 
beaded screen it is a distinguishing feature that the axis moves to 
follow the incident light beam so that a good portion of the light 
is reflected back upon itself. With a metallic screen, the axis is at 
the specular angle. It is planned to make recommendations for the 
types of screen to be employed in theaters of different architectural 
design, as is now being done to some extent, but as yet the Com- 
mittee is not ready to go on record with definite suggestions. 

Variation across Screens. Because of non-uniform light incidence 
over the total area of the screen and because of the non-uniform re- 
flection characteristic, there will usually be variations of bright- 



i^::: -:|::i;p|;u;p 

;:: :.. :: j:.::i::::j:::;i;:;: 





;-:: : |ii!J!i!.-p 



1-4-5 P 









;-;:: r [-:\|;V : . 



Sfrpfe:::: piM: 


= E : 


INtlDpNf J 







: :i;i;;Silin 

::::::::.;:. .-: 

r 1 





0* 60* 

40 20* 20* 40 

&0 8C 


FIG. 2. Distribution of brightness in vertical plane for diffusing screen. 

ness in a projected picture. All theaters are subject to this effect 
at the front of the house but, of course, the continuous change of in- 
tensity in the pictures reduces its noticeability. We shall propose 
limits for allowable brightness differences. 


Theory. The design of screens from the standpoint of sound 
transmission presents problems which are simple in comparison with 
optical considerations. The great importance of good sound trans- 
mission characteristics should, however, be recognized. An analysis 
of the general problem of transmitting sound through a material such 
as a screen indicates several possible methods; certain practical 



considerations, however, limit the designer to the use of two. A 
screen may be expected to radiate sound as a result of being set 
into vibration by sound impulses emanating from the loud speaker 
immediately behind it, or the sound impulses may be transmitted 
through the air spaces in the screen material. These air spaces 
may simply be those due to the porosity of the material itself, but 
better control of the transmission characteristic may be effected by 
deliberately providing air passages of the proper size and number. 
This may be accomplished by careful weaving, punching, or other 
means. All commercial types of screen depend largely upon this 
method of transmission although many depend upon the diaphragm 




FIG. 3. 

20* 0* 20* 


Distribution of brightness in horizontal plane for beaded screen. 

action of the screen to overcome a loss which may occur at low 
frequencies due to a decrease in the radiation resistance of the air 
passages in this part of the frequency range. 

Because of the desirability of affecting the optical characteristics 
of the screen to as small an extent as possible, the perforations or 
air spaces in the screen are made as small as is practicable and their 
number is limited to the absolute minimum. Fortunately, it is 
possible to obtain quite satisfactory sound transmission by using 
rather small, widely spaced openings which, in the aggregate, offer 
a comparatively small total open area in the screen. It is felt that 
an aggregate open area amounting to 5 per cent of the total screen 

Sept., 1931] 



area may be considered tolerable from the light reflection standpoint. 
On this basis it is found that the sound requirements may be met 
without impairing the detail of the picture. The relations between 
the screen thickness and the size and number of the holes may be 
worked out rather easily by applying the known acoustical theory; 
an approximation will serve, however, for the practical designer. 
For perforated screens it has been found, in general, that if the 
diameter of the perforations is equal to three or four times the thick- 
ness, the aggregate area of the openings being 5 per cent of the total 
screen area, satisfactory results may be obtained. This applies to 
the usually used materials and, of course, must at present be con- 
sidered true only for them. Furthermore, it applies only over a 


0* 60" 40* 20* 0* 20* 40* 60" 


FIG. 4. Distribution of brightness in vertical plane for beaded screen. 

limited range of screen thickness. This relation shows that it is 
desirable to keep the screen thickness at as low a value as is mechani- 
cally and optically practical. 

Test. It is the present practice to measure the sound trans- 
mission characteristics or response characteristics of each type of 
screen before approving it for use with sound projecting equipment. 
Although there are various methods by which these acoustical mea- 
surements may be made, the commonly used method involves re- 
sponse-frequency measurements of the output of a loud speaker 
with the screen placed before the speaker in its normal position 
and with the screen removed. In order to adhere as closely as pos- 
sible to actual field conditions in making these measurements, a loud 
speaker of the type used in the field should be employed. Since 



this method of test approximates closely the theater conditions and 
since it includes the effect of the diaphragm action of the screen, 
if present, it is probably the most desirable method of making the 
measurements. The response measuring technic should conform 
with accepted loud speaker response measuring methods. 

Tolerances. There are three factors which must be determined 
before a proper judgment of screen performance may be made. 
The general loudness attenuation effect, the frequency range for 
sound transmission, and the regularity of frequency response all 
enter into the determination of the suitability of a screen from the 
acoustical standpoint. In general, little trouble is experienced in 
obtaining efficient low frequency response. Usually, however. 







20* 0* 20* 


FIG. 5. Distribution of brightness in horizontal plane for metallic screen. 

screens exhibit a drooping characteristic at high frequencies. Since 
the droop at high frequencies is usually rather gradual, no definite 
frequency range may be assigned to the screen response ; the allow- 
able loss at certain high frequency points relative to the 1,000-cycle 
response should be specified. On the whole, it must be observed 
that it is difficult to set absolute limits for screen response, covering 
all possibilities. The following have been applied successfully to the 
great majority of cases by the two largest manufacturers of sound 

A loss of 2.5 db., as given by the average response curve, at 
6,000 cycles, relative to the 1,000-cycle response, is considered 
a desirable limiting value for existing types of sound equip- 
ment. Screens that meet this requirement are usually found to 

Sept., 1931] 



attenuate less than 4 db. at 10,000 cycles. As to regularity of re- 
sponse, variations greater than ==2 db. would not be tolerable. 
Because of standing wave effects in the measuring room, inaccuracies 
of measurement may occur, causing variations somewhat greater 
than this below 300 cycles. It is felt that no limits for regularity 
should apply below this frequency. The interpretation of measure- 
ments must be left to the discretion of one closely acquainted with 
the measuring conditions. A general attenuation in loudness, as 
judged from the measured screen transmission characteristic, greater 
than 1 db., is not considered tolerable. Although this limit may ap- 
pear rather stringent, there are many screens available which meet 




Distribution of brightness in vertical plane for metallic screen. 

this requirement. It seems advisable to maintain this high standard 
for sound transmission. 


The study of screen illumination is one of the primary aims of 
this Committee. We hope to determine average values of bright- 
ness encountered in theaters and to discuss these in relation to stray 
light, print density, and physiological factors. Also, we plan to con- 
sider and standardize methods of measuring brightness, which, at 
the present time, because of their lack of uniformity, render the 
comparison of data difficult. Some information on screen bright- 
ness has been accumulated but not sufficient for presentation at 
this time. 



Rear projection is attracting wide attention at the present time 
in New York and promises to develop into a field of interest through- 
out the country. The manufacturers of this type of screen are not 
as yet willing to release engineering information so that we are 
postponing discussion of this for our later report. 

S. K. WOLF, Chairman 






On account of the wide geographical distribution of the members 
of the Historical Committee it has not been possible to accomplish 
as much as was desired, but largely through the efforts of one of it.s 
members, Mr. W. Theisen, an exhibit of historical films and appara- 
tus was arranged for the Hollywood Convention. It is the hope 
of the Committee that this exhibit has aroused the generosity of 
the members and others who have objects of historical value to the 
end that these objects may be placed in the hands of the Committee 
to be housed in fitting museum repositories where they will be avail- 
able for public inspection, and accessible particularly to the interested 
members of the Society of Motion Picture Engineers. 

Much historical data and records have been collected by the Com- 
mittee and are being classified in loose-leaf binders for final museum 
deposition. Under this classification records are being filed, mainly 
according to outstanding personalities in the early days of the indus- 
try. Among these personalities are included: Georges Demeny, 
Wm. Kennedy Laurie Dickson, Thos. A. Edison, Wm. Friese-Green, 
C. Francis Jenkins, Eugene Lauste, Louis Aime Augustin Le Prince, 
Auguste and Louis Lumiere, Jean A. LeRoy, Ettienne- Jules Marey, 
Eadward Muybridge, and others. 

The Historical Committee wishes to express its gratitude for the 
kindly and generous cooperation and contributions to its work of such 
men as E. Kilburn Scott, London; Will Day, London; Jean A. Le- 
Roy, New York; Wm. Kennedy Laurie Dickson, Channel Islands; 
J. Tarbotton Armstrong, Museum of the University of California; 


J. Waldemar Kaempffert, Museum of Science & Industry, Chicago; 

F. C. Brown, Museum of Peaceful Arts, New York; D. D. Jackson, 
Chemical Museum, Columbia University; A. J. Olmstead, Smith- 
sonian Institute; Dr. Bryan, Los Angeles Museum. 

The Chairman of the Committee also wishes to express his thanks 
to the members of the Committee for their able assistance, particularly 
to the unflagging zeal of President Crabtree, C. Francis Jenkins, Glenn 
E. Matthews, Merritt Crawford, Terry Ramsaye, and W. E. Theisen, 
who have contributed greatly to the work of the Committee. 

A large amount of historical data has been published, both in the 
technical and the popular magazines, and much of the material pub- 
lished has been directly or indirectly the result of the work of the 

The following bibliography for the year past merits consideration: 

"Evolution of Sound Pictures," by M. Crawford, Intern. Photo Bull., Mar., 

"Romance of Photography," Amateur Films, Feb., 1930. 

"On the One-Hundredth Birthday of E. Muy bridge & J. Marey," Camera 
(Luzern), Mar., 1930. 

"Geo. Eastman," by C. W. Ackerman: Houghton Mifflin Co., 1930, 495 pp. 

"Beginning of Amateur Educational Films in the U. S.," by L. M. Bailey, 
Intern. Rev. Ed. Cinemat., March, 1930. 

"New Documents Relating to the Discovery of Photography," by N. E. 
Erincloff, Soviet Photo Almanac, 1929. 

"History of Color Charts," by Prelinger, Kinotechnik, July 5, 1930. 

"Did Edison Invent Motion Pictures?" Mot. Pict. News, July 5, 1930. 

"See and Hear," by W. H. Hays, Mot. Pict. Prod. & Distr. of America, 

"Early History of Photography," by E. Stenger, Camera (Luzern), Aug., 

"Ancestry of Sound Recording," Amer. Projectionist, July, 1930. 

"A Motion Picture Made in 1916 by a Two-Color Subtractive Process," by 

G. E. Matthews, /. Soc. Mot. Pict. Eng., XV, No. 11 (Nov., 1930). 

"Louis Aime Augustin Le Prince, a Father of Motion Pictures," Kinotechnik, 
Sept. 20, 1930. 

"Story of Sound Films," by K. Teuke, Kinotechnik, Feb. 5, 1930. 

"From Flickers to Movies to Talkies," by O. F. Spahr, Ex. Herald-World, 
June 7, 1930. 

"Role of Dyes in the Progress of Photography," by A. Seyewetz, Photo Revue, 
Dec. 1, 1930. 

"Scientific Cinematography and the Work of Dr. Jean Comandon," by C. M. 
Croissac, Intern. Rev. Ed. Cinemat., Sept., 1930. 

"When the Movies First Tried to Talk," by H. S. Hulfish, Ex. Herald-World, 
Aug. 30, 1930. 


"Through a Yellow Glass," O. Blakeston, Pool, London, 1930, 138 pp. 

"Film Technique," by V. I. Pudovkin, V. Gollanz, Ltd., London, 204 pp. 

"Meaningless Jubilee," by G. Seeber and K. Walter, Filmtechnik, Nov. 15, 

"The Projector Has a Birthday," by Chas. Hastings, Mot. Pict. News, Feb., 

"William Friese-Green, England's Great Cinematographer," by M. Crawford, 
Cinema, Sept., 1930. 

"A Mystery of the Motion Picture's Beginnings," by M. Crawford, Cinema, 
Dec., 1930. 

"First Days of the Movies," Literary Digest, Jan. 10, 1931. 

"Los Padres del Cine," by M. Crawford, Cine-Mundial, Feb., 1931. 

C. L. GREGORY, Chairman 









During the Spring, 1931, Meeting at Hollywood, Calif., motion 
pictures, taken thirty-four years ago by Mr. Oscar B. Depue, of Chi- 
cago, were projected. In addition to these, a sound picture was pro- 
jected which showed Mr. Depue addressing the meeting, and in 
which were included views of the telegraphone illustrated below. 

The words by Mr. Depue, addressed to the Society from the screen, 
were as follows: 

"You have just seen motion pictures that I made thirty-four years ago. They 
are reduction prints made from 60-mm. negative. The very first one that I 
made was in front of St. Peters in Rome, the grandest of all cathedrals; with the 
Vatican, the fountains, and the goats in the background; then the gondolas, in 
Venice, in front of the Piazzetta on the Grand Canal; later, the Plaza in front 
of the beautiful Milan Cathedral, and the Place de la Concord at the entrance of 
the Champs-Elysees. These were made over a third of a century ago. Now I 
want to take you back a quarter of a century and give you a few examples of early 
sound recording. 

* A contribution to the Historical Committee Report. Presented at the 
Spring, 1931, Meeting at Hollywood, Calif. 


"It was while touring Europe with Burton Holmes in 1907 that I first learned 
about the Poulsen telegraphone, a marvelous little instrument that recorded sound 
magnetically on a fine wire. I was fascinated with the thought of recording the 
voice electrically; whereupon I went to Copenhagen and purchased this early 
model telegraphone. It is machine number 41. 

"On the steamer coming home I had it set up in my cabin, and passengers hear- 
ing about it used to make short records and were delighted to hear their own voices 
reproduced through the head-phones. 

"Among the passengers was the late James Powers, the Irish comedian. Mr. 
Powers gave several selections and at the end of one of them gave the date of the 

"When I reached my home I could not operate the instrument as my home was 

FIG. 1. Mr. Depue's Poulsen telegraphone used for magnetically recording 
sound on wires in 1907. 

not wired with direct current and so the machine has been falling to pieces during 
these years while lying in my den. 

"Mr. Walter Hotz, sound engineer for the Industrial Division of the Burton 
Holmes Lectures, told me one day that he thought he could trace out the broken 
circuits of the machine and get it to operate, and that if anything remained of 
the records he probably could amplify it and reproduce it on film. Thanks to 
his patience in repairing the machine and in untangling some of the awful 
messes that the wire reels go into, we have been able to reproduce for you, with 
ample volume for an audience to hear, those old records. I cannot detect 
any appreciable loss of characteristics and volume during these 24 years of 

"I am sorry circumstances prevented me from attending the convention in 
person. I should like very much to hear the able papers and discussions and I 
should like to ask that you consider Chicago for the Fall Convention. 


"Now, Mr. Chairman and fellow members of the Society, as usual, I have 
talked too long and I know you are waiting to hear Mr. Powers give you 'Sally, 
in Our Alley.' " 

The sounds recorded magnetically by the telegraphone, in 1907, 
to which Mr. Depue referred in his talk, were reproduced from 
film for the audience to hear. Mr. Depue's talk, reproduced from 
the continuation the film, was as follows: 

"Perhaps you would like to see the telegraphone in operation. To make a 
recording you touch the forward button; then you plug in the microphone and 
talk into it at rather close range. Now, to reproduce, you push the stop button 
and then the 'backward' button, rewinding as far as you wish. Now, remove the 
microphone plug and start the machine forward. The head-phones will give a 
reproduction. If you should leave the microphone plug in while reeling forward, 
any message on the wire would be wiped off. The wire may be used any number 
of times. 

"A look at the inside shows how complicated and delicate it really is. I do 
not know how it can be used in the industry unless, possibly, for play-backs for 
a quick check up. But I think this form of machine is far too complicated and 
the wire too delicate and subject to breakage and tangling to be practical." 


The present committee, with a slight variation of members, has 
operated as the Membership Committee since 1928, and has made a 
thorough investigation of the eligible or potential members in the 
motion picture engineering field. In 1930 it undertook the work of 
increasing the number of non-member subscribers to our JOURNAL, 
and thus became the Membership and Subscription Committee. 

The Committee believes that the present entrance fees and dues, as 
well as the JOURNAL subscription rates, are entirely too high compared 
with the charges of other societies and the cost of subscriptions for 
their technical publications. As a result of our high rate of dues, a 
large number of eligible younger workers are being kept out of the 
Society. These must resort to reading JOURNALS borrowed from 
friends, or lack the publications. 

As the object of this Society is the dissemination of scientific in- 
formation, and as the Society has already a number of substantial 
sustaining members among the manufacturers and producers, we 

* Presented at the Spring, 1931, Meeting at Hollywood, Calif. 


feel that the annual associate dues and the JOURNAL subscription rate 
should be reduced to such amounts as would permit a greater dis- 
tribution of the JOURNAL. We feel that the subscriptions for the 
JOURNAL should not cost more than six dollars per year. At this 
reduced rate the subscription list could easily be increased to one 
thousand subscribers within a year. 


October 1, 1930. Total members (active and associate) 748 

Deliquencies from Oct. 1, 1930, to May 25, 1931 90* 

Resignations 22 

Deaths 114 

Total 634 

New members (Oct. 1, 1930, to May 13, 1931) 97 

Applications pending 18 

Total 115 


Number of non-member subscribers to the JOURNAL 250. 
* Disbandment of the London section resulted in loss of about 60 members in 
resignations and delinquents or abandonment of membership. 


Sections or Countries Active Associate Total 

New York Section 195 184 379 

Chicago Section 27 50 77 

Pacific Coast Section 30 53 113 


Argentina 1 1 

Austria 1 1 

Australia 134 

Canada (> 10 16 

England 19 43 62 

France 10 16 26 

Germany 9 11 20 

Hawaii 1 1 

Holland 1 1 

India 4 10 14 

Italy 2 2 

Japan 235 

New Zealand 1 1 

Norway 1 1 

Poland 1 3 



Sections or Countries 

South Africa 
West Indies 


Active Associate Total 

2 2 





Total Membership 731 
Applications Pending 18 

H. T. COWLING, Chairman 









Sensitometric Control in the Development of Sound Films II. ALFRED 
KUSTER AND RICHARD SCHMIDT. Kinotechnik, 13, April 5, 1931, pp. 123-6. 
Sensitometric control in the development of variable density sound films is main- 
tained by means of an exposing box and an Agfa gammameter. A strip of film is 
exposed on the box which has a Sensitometric scale of five different densities in 
steps of 0.25. This strip is developed with the sound film and then placed on the 
gammameter to determine the gamma. This instrument has 12 rows of 5 densities 
each, corresponding to 12 different gammas, placed over an opal glass illuminated 
from below. When the film is placed on the gammameter with the densest step 
on the film over the series of light steps of the gammameter, it is found that the 
five steps of the film strip assume a uniform density when they cover the five steps 
of one of the rows of the instrument. The gamma corresponding to this row is 
then read directly and is the same as the gamma of the strip. 

It has been found that with constant development, the gamma of a sound film, 
as determined by its effect on a photoelectric cell, differs from that of a Sensito- 
metric strip measured in contact with an opal glass on account of two effects which 
act in opposite directions. The first is the Callier effect, as a result of which the 
sound record has a gamma 1.2 times that of the Sensitometric strip. The second 
is the Schwarzschild effect, resulting from the difference in exposure time and 
intensity of the Sensitometric strip and sound record. This causes the sound film 

to have a gamma ~~z as high as that of the Sensitometric strip. This factor was 

found to hold for Agfa 12 developer for a number of varieties of sound film and 
different development times but is different for different developers. The product 

of the factors, ~ , is the factor by which the gamma of the Sensitometric strip 

must be multiplied to find the gamma of the sound record with the same develop- 
ment. This factor is valid for Agfa 12 developer only. M. W. S. 

The Problem of Sound Motion Pictures by Radio. FRITZ WINCKEL. Kino- 
technik, 13, Feb. 20, 1931, pp. 64-5. A German television receiver serves for 
the reproduction of standard sound films, since it operates with 1,200 picture 
elements and 25 pictures per second. The transmitter consists of a sound 
film projector in connection with a Nipkow scanning disk. The film moves 
continuously in the projector. It is claimed that the picture quality appears 
better as a result of the accompanying sound reproduction. Another receiver 
employs 12.5 pictures per second to conform with the standards of the German 
Postal Service. The sound accompaniment is said to have a favorable effect upon 
the picture quality in this apparatus also, although the picture quality is not as good 
as in the former apparatus. The 12.5 pictures per second are transmitted by the 
aid of an optical device with mirrors and lenses which combines two succeeding 
pictures, the combined picture being scanned. The broadcasting of sound films is 
being considered in Germany. It is hoped that a 42-hole scanning disk instead of 



the present 30-hole disk will be employed, and that 25 pictures per second will be 
sent. Short-wave transmission will be necessary. It is also hoped that the 
sound film standard will be changed to 25 pictures per second. M. W. S. 

A Consideration of Screen Brightness Measurements in Motion Picture 
Theaters. H. SCHERING. Kinotechnik, 13, Feb. 20, 1931, pp. 59-63. Measure- 
ments were made of the intensity of illumination and visual brightness of the 
screens of eight Berlin theaters and two Dresden theaters. It is concluded that 
in the projection of black-and-white films on solid screens, great economy of 
current could be achieved in the smaller theaters by the use of automatic feeding 
devices for the carbon arcs; that in the larger theaters with screens over 6 meters 
in width, the projection apparatus installed is hardly adequate; and that in 
almost all cases the screen is in such poor condition that the minimum screen 
brightness required is not attained. 

Data were obtained for three theaters having porous screens for sound film pro- 
jection. In all cases, the visual brightness of the screen was far below the re- 
quired value on account of the poor reflecting power of the screen. The bright- 
ness calculated on the basis of a more efficient sound film screen of 65 per cent 
reflecting power is still too low. In the two larger theaters, it was found that 
the projection apparatus was inadequate even with efficient adjustment. 

On the assumption that color films require twice the illumination required for 
black-and-white films, it is concluded that the projection apparatus in the thea- 
ters having screens 4 meters in width would still suffice for sound films in color, pro- 
vided that automatic feeding of the carbons were employed. The theaters having 
screens over 6 meters in width would require a thorough change in the illuminating 
system in order to elfect a material increase in the illumination. This cannot be 
effected by increasing the current or the aperture of the mirror, and must be 
done by increasing the intrinsic brightness of the crater. The author concludes 
that the arcs with high intensity (cored) carbons must be adopted in Germany 
for the projection of color films. Illustrations are given of American and German 
high intensity arc lamps for projectors. M. W. S. 

A Recent Demonstration of Television and Telecinema. A. LOVICHI. Tech- 
nique Cinemat., 2, Mar.-April, 1931, p. 17. A demonstration of the Barth6- 
lemy system of television is described. The transmitter employs a Weiller 
scanning disk, a horizontal wheel carrying on its periphery thirty mirrors inclined 
at varying angles to the axis. The scanning beam is reflected from these mirrors 
to the subject and then to the photoelectric cells. There is a brief lapse between 
the end of one scanning line and the beginning of the next, and these lapses add a 
480-cycle frequency to the image modulation. This frequency, filtered by an in- 
genious amplifying circuit, is used to operate a synchronous motor which drives 
the receiving scanning disk. The reproducing circuit is not described, but it is 
claimed that a 3-watt neon lamp is used for a picture area of 600 square centi- 
meters as opposed to a 250-watt lamp for a picture area of 6 square centimeters 
in the American system. H. P. 

Temperature Control during Film Development. T. THORNE-BAKER. Kine- 
mat. Weekly (Supp.) 172, June 18, 1931, pp. 41, 43. The importance of accurate 
control of the temperature during film development is stressed. Equal results 
may be obtained within the temperature range of 58 F. to 75 F. if the time of 
development is correspondingly altered in accordance with the temperature co- 

Sept., 1931] ABSTRACTS 457 

efficient of the particular developing agent used. The temperature coefficient 
is a measure of the relative increase of the velocity of development produced by a 
rise of temperature of 10 degrees Centigrade (18 F.) and may be obtained from 
the following relation: 

log /i - log / 2 X 10 

T 2 - 

log c, 

where t\ and /2 are the times of first appearance at the Centigrade temperatures 
T\ and T 2 , respectively, and c is the temperature coefficient. (The terms in the 
published formula are confused and the substitution given in the example is in- 
correct, although the correct answer is shown.) 

The use of a Dewar flask or thermos bottle is mentioned for the constant tem- 
perature development of test strips of film. Electrical heating of the processing 
solutions may be controlled conveniently by the use of thermostats of the usual 
mercury contact type or with a Lowry type of tube, which contains in the ex- 
pansion bulb a liquid of low specific heat and high coefficient of expansion, such as 
toluine or aniline. With electrical thermostats two stages of relays are necessary, 
one for the weak thermostat current and a second more robust instrument for the 
heater current. Heaters of 300 watts capacity per 2 gallon quantity of solution 
are suggested. The temperature of the solutions may also be controlled by the 
room temperature, and a brief description is given of methods used by English 
firms. The necessity for refrigeration during certain seasons is indicated, but no 
description of equipment is given. L. E. M. 

The Trans-Lux System of Operation. GEORGE SCHUTZ AND F. H. RICHARDSON. 
Mot. Pict. Herald, 103, Sect. 2, May 9, 1931, pp. 12-3. A description of the 
first of a chain of small theaters seating 150" to 200 patrons. This theater is 45 
feet long by 30 feet wide by 14 feet high, and seats 158 persons. Rear projection 
is used, the projectors being located about 10 feet behind the screen. (The 
Trans-Lux lens system requires that there be an inch of projection distance allowed 
for each square foot of projected image.) Horns are located at the sides of the 
screen. The film is reversed (left to right) before placing in the projector, and the 
entire sound head is located on the right side of the projector pointing backward. 

G. E. M. 

Recording Processes for Sound Films. Technique Cinemat., 2, Mar.-April, 
1931, pp. 22-39. Descriptions of the following processes are given: Tobis, 
Gaumont-Peterson-Poulsen, Western Electric, and Stille. Diagrams and illustra- 
tions are included. G. E. M. 

Natural and Unnatural Synchronism. R. THUN. Kinotechnik, 13, March 1, 
1931, pp. 93-5. In natural synchronism, the pictorial representation of the 
process producing the sound and the reproduction of the sound by the loud speaker 
have a time relation corresponding to reality; while, in unnatural synchronism, the 
process apparently producing the sound coincides exactly with the reproduction of 
the sound by the loud speaker. Some of the principles of synchronizing with a 
picture speech in a foreign language are described to illustrate the complexity of 
the time relation between sound and picture that is denoted by the word "syn- 
chronism." For a proper artistic effect, natural synchronism is required, and 
not the unnatural synchronism demanded by hypercritical observers. M. W. S. 

The New Sound Film Apparatus of Tobis-Klangfilm for News Recording. 



[J. S. M. P. E. 

J. KIRSTAEDTER. KinoUchnik, 13, March 1, 1931, pp. 91-3. The motion 
picture camera and sound recording apparatus are fitted into a large limousine. 
Pictures may be taken from the moving car, or the camera may be set on a tripod 
on the ground or on top of the car. Current is supplied by storage batteries. 
Plate, grid, and Kerr cell potentials are supplied by dry batteries. M. W. S. 

The Debrie Sound Film Camera. L. KUTZLEB. Kinotechnik, 13, March 1, 1931, 
pp. 88-91. The Debrie "Parvo T" camera differs from the previous model "L" 
principally in having larger film magazines which hold 300 meters of film to meet 
the requirements of sound films with 24 pictures per second and longer scenes. 
Upon throwing the switch the motor does not immediately attain its full speed, but 
reaches full speed very quickly. This is done to avoid straining the mechanism. 
In the event that the motor should be started when the camera is not ready to 
operate, or that an accident should occur during operation, a wooden coupling 
breaks in the driving mechanism between the motor and the camera. Another 
device stops the motor by electromagnetic means if the film is not fed properly 
through the gate. Registration marks for synchronizing may be applied at the 
edge of the film by a lamp or in the picture area immediately below the aperture 
by means of a punch. In order to reduce noise, the camera housing is lined 
with rubber, and the gears are constructed of such materials that steel does not 
work upon steel. A second sound absorbing case covers the entire camera, pro- 
vision being made for making adjustments on the camera with the case closed. 
The camera and case are balanced in trunnions on the tripod. A long handle, 
instead of cranks, serves for panoraming and tilting. The usual form of tripod, 
with metal braces, is used out of doors, but a heavy column type of stand is used 
in the studio. One form of studio stand is operated entirely by electric motors. 

M. W. S. 

The Selenophon Recording and Reproducing Apparatus. G. E. ROTH. 
Kinotechnik, 13, March 1, 1931, pp. 84-8. The Selenophon sound recording 
apparatus employs a wire under tension between the poles of an electromagnet. 
When at rest, the wire covers half the light image of a slit. When current from a 
microphone flows through the wire causing it to vibrate, it uncovers more or 
less of the slit image. The device may be used for either the variable width or 
variable density method of sound recording. In the variable width method, the 
wire is placed at a slight angle to the slit, so that the length of the slit image 
changes. In the variable density method, the wire is placed parallel to the slit 
so that the width changes. In practice, the Selenophon Company uses the 
variable width method. Eight sound records are made in the width of a 35 mm. 

The reproducing apparatus employs a selenium cell of the condenser type. 
In this cell a condenser is cut perpendicularly to the plates so that the edges of the 
interlocking plates are exposed. A thin layer of selenium forms a conducting 
medium between the edges of the plates. This device is built into apparatus 
that can be attached to a standard motion picture projector. 

The Selenophon Company also makes three models of apparatus for reproducing 
sound without pictures for home use. M. W. S. 

Notes on Loud Speaker Response Measurements and Some Typical Response 
Curves. BENJAMIN OLNEY. Proc. L R. E., 19, No. 7, July, 1931, p. 1113. 
The difficulties encountered in the measurements of loud speaker output are de- 

Sept., 1931] ABSTRACTS 459 

scribed. A typical set-up for taking curves indoors is explained. Greater ac- 
curacy of measurement, especially in the low-frequency range, is obtained by mak- 
ing measurements out of doors. An out-door set-up for making loud speaker out- 
put measurements is explained and illustrated. The effects of various corruga- 
tions in loud speaker cones, and the effects of different types of baffles are illus- 
trated by numerous curves. The interpretation of loud speaker response curves 
is shown to be a comparative interpretation rather than a direct reading of what 
one may expect to hear. A. H. H. 

High Audio Power from Relatively Small Tubes. L. E. BARTON. Proc. 
I. R. E. t 19, No. 7, July, 1931, p. 1131. The reasons for the development of 
the present power output tubes are pointed out. Class "A" amplifiers are ex- 
plained as well as the factors limiting the power output of such amplifiers. It is 
shown that the output load resistance for maximum undistorted power output is a 
function of the plate current and plate voltage, and is practically independent of 
the plate resistance and amplification constant, provided the grid swing is not 
limited. The principles of operation of class "B" audio amplifiers are thoroughly 
explained with the aid of numerous diagrams. The power output of a class "B" 
amplifier is limited only by emission or plate dissipation on peak signals. For 
class "B" amplifiers the bias supply must be well regulated or batteries must be 
used. A. H. H. 

The Prevention of Interfering Noises. P. T. SHERIDAN. Motion Picture 
Herald, Section 2, July 4, 1931, p. 31. This article, the first of three on this 
subject, although non- technical, is of interest to the engineer. It covers those 
noises which are transmitted through the air to the theater audiences. Several 
sources of noises and possible corrective measures are given. Projectionists' 
conversations, loud operation of the monitor speaker, handling of film, poor reels, 
and noises from the projection machine itself are mentioned as possible sources of 
this type of noise. A. H. H. 

The Measurement of Reverberation Time and Its Application to Acoustic 
Problems in Sound Pictures. F. L. HOPPER. /. Acoustical Soc., II, No. 4, 
April, 1931, pp. 499-505. A reverberation time meter is briefly discribed. The 
results of typical measurements are shown, including the reverberation time vs. 
frequency curves of two sound stages, a theater before and after acoustical treat- 
ment, and the absorption-frequency characteristics of acoustic building board and 
rockwood. W. A. M. 

A Direct Reading Audio-Frequency Phase Meter. W. R. MACLEAN AND 
L. J. SIVIAN. J. Acoustical Soc., II, No. 4, April, 1931, pp. 419-33. A direct 
reading audio-frequency phase meter, which includes a cathode ray oscillograph 
and special vacuum tube circuit, is described. As an illustration of the type of 
work to which this phase meter is well suited, an acoustical experiment is de- 
scribed in which the response vs. frequency and phase angle vs. frequency of each 
of two microphones, hung indoors, are measured in detail between 1,500 and 1,505 
cycles per second. Their combined outputs are also studied and show, in this 
particular case, a variation of almost 30 db. in response and a variation of over 
100 degrees in phase angle within this frequency band only five cycles wide. 

W. A. M 

A New High Efficiency Theater Loud Speaker of the Directional Baffle Type. 
HARRY F. OLSON. J. Acoustical Soc., II, No. 4, April, 1931. A description 

4(iO ABSTRACTS [J. S. M. P. E. 

of a new directional baffle speaker together with a theoretical discussion of design. 
Curves showing the efficiency vs. frequency, response vs. frequency, and direc- 
tional properties of the speaker are included. W. A. M. 

Sound Pictures: Fundamental Principles and Some Factors Which Affect 
Their Quality. F. L. HUNT. /. Acoustical Soc., II, No. 4, April, 1931, pp. 
476-84. This paper reviews the fundamental principles of sound picture record- 
ing and reproduction on disk and film, showing that sound pictures in the modern 
sense were dependent on the development of the vacuum tube amplifier which 
made available adequate energy for recording and reproduction, and also on the 
use of electrical methods of synchronization and speed control. The present 
status of the art relative to frequency and volume ranges and the effect of limita- 
tions in these factors on quality is then discussed. The effect of reflected sound 
reverberation on the fidelity of recording in the studio and on reproduction in 
the theater is also considered. The best articulation is obtained when reflected 
sound is not present, but some reflection is usually necessary to maintain the 
illusion that the sound was produced under the conditions depicted in the scene. 
The high per cent of articulation obtained by experiment with standard reproduc- 
ing equipment indicates that little difficulty should be experienced in understand- 
ing as far as equipment is concerned. This shows the importance of good audi- 
torium acoustics. W. A. M. 

Acoustics of Music Rooms. VERN O. KNUDSEN. 7. Acoustical Soc., II, 
No. 4, April, 1931, pp. 434-67. This paper "represents an attempt to consider 
the problem of music room acoustics in the light of recent developments in 
acoustics and the tested results of experience; and to call attention to certain 
problems which require further investigation." The ideal conditions for the artis- 
tic production of music and the conditions for listening to music are listed and 
discussed. These include freedom from noise; the proper arrangement of spaces 
for orchestra, soloist, chorus, organ, and audience; proper loudness; proper rever- 
beration characteristics ; resonance ; echoes, interfering reflections and sound foci ; 
and variation of the acoustical properties of a room with the size of the audience 

A section is devoted to data recently collected by the author regarding the acous- 
tics of thirteen European music rooms. The many factors affecting the acoustics 
of these, of which the reverberation time of each is only one factor, are weighed 
and discussed. The apparent need for resonant panels of wood or plaster, or both, 
as a part of the ideal music room, is emphasized. The data also indicate that 
the reverberation times of those music rooms which enjoy the best reputations 
are shorter than have generally been accepted as optimal in the past. An ex- 
ample of the general point of view of the author is illustrated as follows: 
"Here, as in the Musikvereinssaal, good acoustical properties are identified with 
rather short reverberation times (1.35 and 1.5 seconds at 512 d.v., and about 
double these values at 128 d.v.), with shapes that are free from pronounced 
concave surfaces, and with rooms that are bounded, in large part, with resonant 
materials. It should be mentioned also that both halls are remarkably free from 
outside noises." 

A very practical conclusion to the paper is given in four illustrations giving 
plans of four music rooms, varying in size from a small music studio to an opera 
house, such that they embody the desirable features of design advocated in the 
text. W. A. M. 

Sept., 1931] ABSTRACTS 461 





HAAK, A. H. McNicoL, D. 








Reissue 18,108. Producing Silent Intervals on Sound Tracks. LEE DE 
FOREST. Assigned to General Talking Pictures Corporation. June 23, 1931. 
Silent intervals may be produced on the photoelectric sound track of a sound-on- 
film positive and the sound track freed of any densities in the emulsion of the film 
that may produce ground noises by blackening the positive at all portions of 
the sound recording part of the film where silence is desired. The developed 
sound-on-film negative produces a sound track on a positive film and the two 
films are run through a printer where an auxiliary printing light produces a 
blackened interval on the positive film where silence is desired. 

In order to blacken the positive film at appropriate intervals the negative or 
master film is provided with notches at those portions where a blackened positive 
is to be produced. These notches serve to control the operation of a switch which 
cuts on or off the auxiliary printing light to produce the silent portions of the 
positive film. 

1.809.815. Safety Device for Motion Picture Projecting Machines. J. F. 
ADAMS. Assigned to Sentry Safety Control Corp. June 16, 1931. Safety cut-off 
and douser for protecting the film against ignition in the event that the driving 
motor on the projector should drop below a predetermined speed. A mercury 
switch is provided for interrupting the motor circuit when the speed falls below a 
predetermined value. A shutter is also electromagnetically actuated for obstruct- 
ing the rays of light passing through the film when the speed falls below a safe 

1.809.816. Centrifugal Switch for Controlling Film Feeding Mechanism. 
J. F. ADAMS AND THOMAS T. ALLEN. Assigned to Sentry Safety Control Corp. 
June 16, 1931. The film feeding mechanism is controlled by means of a centrifugal 
switch. The centrifugal switch has contactors which, when the film feeding 
mechanism and switch are operated at a predetermined speed, are held outward 
centrifugally. However, when the film feeding mechanism and switch fall below 
the required speed, the contactors are swung inward and make contact with the 
contact rings which break the motor circuit, and stop and intercept the light rays 
upon the film. By means of the centrifugal switch the proper filming may be 

1.809.817. Safety Unit for Motion Picture Projectors. THOMAS T. ALLEN 
AND JOHN F. ADAMS. Assigned to Sentry Safety Control Corp. June 16, 1931. 
A safety switch for motion picture projectors which operates if the film fails to 
move at or about a certain speed through the path of the rays of light emanating 
from the projection lamp to cut off the light rays and bring the projector to a stop. 
A unit is provided for stopping the projecting mechanism and intercepting the 
rays of light passing through the film upon the occurrence of any incident or 
accident which might cause the film to ignite. The safety device includes an 
electromagnet, a relay system, and a centrifugal switch electrically connected 
with the motor circuit and arranged to control a shutter mechanism for insuring 


the safety control of the projector in the event of an accident giving rise to fire 

1,810,002. Film Marking Device. JOHN ARNOLD. Assigned to Metro- 
Goldwyn-Mayer Corp. June 16, 1931. An auxiliary shutter is mounted upon 
a motion picture camera and operated by an electromagnet for exposing the film at 
selected time intervals with light for marking the film at any given position. The 
arrangement of the auxiliary shutter and electromagnetic actuator is very 
compact, for placing a light spot on the film to form an identification means for 
that portion of the film after development. 

1,810,062. Wax Record Synchronized by Timing Strip on Film. E. R. 
TAYLOR. June 16, 1931. A wax record type of phonograph is used in coopera- 
tion with a motion picture projecting machine and synchronized in operation by a 
timing strip which runs in synchronism with the picture film. The timing strip 
carries contact members at predetermined intervals adapted to close a circuit to an 
electromagnetic actuator for engaging or disengaging the stylus with the sound 
record in timed relation to the movement of the picture film. 

1.810.168. Motion Picture Screen Employing Embedded Glass Cylinders. 
J. A. GRAY. June 16, 1931. A covering layer of solid glass cylinders is imbedded 
in and applied to an adhesive coating on a fabric backing, which forms the motion 
picture screen. The solid glass cylinders are approximately VM of an inch in 
diameter and about Vie of an inch long. These glass cylinders constitute the 
facing of the screen, lying in all sorts of varying flat-wise positions upon the fabric, 
and the light thrown against the face of the screen is condensed in the usual 
manner and reflected therefrom at the different angles of both the end walls and 
the circular walls of the cylinders. The end walls of the cylinders face other ad- 
jacent cylinders at all sorts of varying angles and there will be an extreme varia- 
tion, both of the angles of the rays of reflection and of the angles of the rays of 
refraction in rays passing from one cylinder to another cylinder and being then 
reflected and refracted. Since the light is reflected and refracted at every con- 
ceivable angle, the field of illumination is materially spread beyond the sides 
of the screen. 

1.810.169. Backing for Motion Picture Screen. J. A. GRAY. June 16, 1931. 
A projection screen for talking motion pictures where a porous backing member is 
provided for the free passage of sound from a sound reproducer in the rear of the 
screen through the screen. The threads of the backing member are coated with a 
pigment compound and then a layer of small cylindrical glass particles deposited 
over the compound. The glass cylinders serve to increase the lateral diffusion 
while permitting the free passage of sound through the screen. 

1,810,188. Television System. T. A. SMITH. Assigned to Radio Corporation 
of America. June 16, 1931. Transmitting system for televising motion pictures, 
where the number of complete television images to be transmitted per second is 
different from the number 6f frames on the transmitted film which normally pass 
the projector aperture or scanning device in the same period of time. The motion 
picture film is, in effect, transmitted over a television transmitter at a speed lower 
than that at which it was originally made to be run, while, at the same time, the 
sounds accompanying the film may be transmitted at the proper speed for which 
it was originally produced. The scanner is operated in conjunction with a 
shutter mechanism by which a motion picture film may be moved at a predeter- 


mined constant speed relative to a predetermined point and a smaller number of 
picture frames of the motion picture film scanned than the number of picture 
frames which pass before the predetermined point during a unit time period 

1,810,200. Printing Machine for Colored Films. P. BROSSE. Assigned to 
Kislyn Corporation. June 16, 1931. A projection printing machine for repro- 
ducing color prints on film according to the Berthon process. Essentially, the 
apparatus comprises a conventional projection printing machine which is pro- 
vided with two passing devices whereof the mechanisms have a reversed action 
with respect to each other; in the one the original film is passed downward; in 
the other the copy is passed upward. Between these mechanisms is located the 
optical system by means of which the original film is projected on the virgin film 
by means of a light source illuminating the original film. 

1,810,234. System for Optically Recording Phonograph Records. Assigned 
to Radio Corporation of America. June 16, 1931 . A diaphragm is arranged to be 
moved in accordance with sound vibrations, and is linked to variably tilt a reflect- 
ing mirror in accordance with variations in the amplitude of the sound vibrations. 
The reflected light is directed toward a rotatably mounted light-sensitive disk by 
which a trace may be made on the light-sensitive disk. The light-sensitive disk is 
mounted on a carriage adjustable toward or away from the movable mirror. The 
disk is rotated by a gear system which meshes with teeth formed in the peripheral 
edge of the rotatable carrier for the disk. 

1,810,324. Multiple Channel Sound Reproducing Apparatus. F. H. OWENS. 
Assigned to Owens Development Corp. June 16, 1931. A multiple channel 
sound film is employed wherein one channel contains a sound record includ- 
ing sound within a particular range of frequencies, while the other channel con- 
tains sounds within a different range of frequencies. Separate photoelectric cells 
with control circuits connected thereto are aligned with the different sound chan- 
nels and connected to a sound reproducer circuit. A shutter mechanism contain- 
ing apertures adapted to be aligned with either of the sound channels and the 
associated photoelectric cell is arranged adjacent the film and is driven by a 
solenoid which is energized from a switch automatically actuated by an arm 
engageable with notches cut at predetermined points along the edge of the film. 
The notches are so arranged along the film that the shutter mechanism may be 
shifted from one position to another to select the order of reproduction on the 
different sound films. 

1,810,346. Motion Picture Screen for Stereoscopic Effect. E. M. CRAWFORD. 
June 16, 1931. Motion picture screen formed of sections which are adjustable 
along a transverse axis into different planes of rotation for the reproduction of a 
picture which will have a stereoscopic appearance. The different sections of the 
screen are adjustable transversely with respect to a central rotatable shaft which 
will provide different angularly disposed display surfaces for the picture. As 
these surfaces are rotated at a rate of 16 rotations of more per second the illu- 
sory effect of two visible screens, one behind the other, will be created and the pro- 
jected pictures will be seen on both screens, thus giving a depth, or stereoscopic 

1,810,348. Douser Control Mechanism for Motion Picture Projectors. 
J. T. FEWKES. Assigned to Sentry Safety Control Corporation. June 16, 1931. 
An electromagnetic actuating device which normally holds a shutter out of the 

Sept., 1931] PATENT ABSTRACTS 465 

light-obstructing position when the electromagnetic device is energized during 
the normal operation of the projection machine. However, in case of defective 
filming, such as breaking or clogging of the film, the electromagnetic actuator acts 
to automatically shut off the passage of light rays and to open the circuit of the 
driving motor. After correction of the defect, the douser is automatically re-set 
in the safety position for a successive operation. 

1,810,605. Modulating Light Beam by Variation of Air Density Caused by 
Sound Waves. H. P. HOLLNAGEL. Assigned to General Electric Company. 
June 16, 1931. A beam of light is focused to pass through a point of concentra- 
tion. Sound waves are directed upon the beam of light at the point of concentra- 
tion thereof for modulating the light rays. The light rays may be focused upon a 
film and modulated in accordance with the impression of sound waves at the point 
of concentration of the light beam. In order to concentrate the sound waves a 
conical shaped member is arranged to lead the sound waves to the small open end, 
and at the focal point of the light beam where the density of the air is changed 
to produce corresponding variations in the refraction of the light beam at that 

1,810,703. Blue Color Filter for Kerr Cell Employing Nitrobenzol. W. 
GALL AH AN. Assigned to Westinghouse Electric and Manufacturing Company. 
June 16, 1931. A Kerr cell utilizing nitrobenzol for its dielectric is employed to 
control the passage of light to the light-sensitive film during the recording proc- 
ess, and a color filter transparent to blue light is interposed in the path of the 
light rays. The color filter, which is transparent to blue light, compensates for 
the yellow color of the nitrobenzol. The nitrobenzol has a natural yellow color 
which tends to increase the blurring effect of yellow light on the film. How- 
ever, with a color filter transparent to blue light, such as a piece of gelatin dyed 
blue by means of aniline dye, this blurring effect is counteracted. 

1,810,705. Thermal Sound Recording System. E. H. HANSEN. June 16, 
1931. Recording apparatus for impressing sound on wax records where the 
recording head functions with a preformed disk for engraving a sound record in 
the disk by a thermal process. The recording stylus is electrically heated for 
thermally cutting a record in the disk in accordance with sound variations. 

1,811,365. Roller Support for Traveling Films. F. H. OWENS. Assigned to 
Owens Development Corporation. June 23, 1931. A sound and picture film 
is guided over a fixed arbor which has rotatable sleeves journaled thereon for 
providing a support for the film during the passage of the film over the arbor. 
The rotatable sleeves extend toward each other along the arbor and are separated 
by a predetermined gap. An aperture extends diametrically through the arbor 
in the gap formed between the ends of the sleeves, and provides a light passage for 
the light rays which pass through the sound channel on the film for actuating a 
photoelectric cell aligned with the aperture through the arbor. 

1,811,495. Multiple Image Camera. H. N. Cox. Assigned to Cox Multi- 
Color Photo Company. June 23, 1931. A lens system wherein multiple-image 
work may be substituted in a camera for the usual single-image lens and when so 
substituted is capable of affording a plurality of images in which aberration due to 
parallax as well as to the optical properties of the lenses is not greater than the 
aberration which in the single-image system is due solely to the optical properties 
of the lens. The multiple-image lens projects the light upon a film within the 


area covered by the single-image lens, providing multiple images of equal angle of 
view. The multiple-image lens system includes a plurality of identical lens units, 
and a fixed aperture symmetrically spaced about an axis, the focal length of the 
lenses being substantially 5/8n X w, in which n equals the numerical aperture 
of the lens units of the multiple-image system, and w equals the width of the film 

1,812,068. Footage Indicator for Motion Picture Cameras. A. F. VICTOR. 
June 30, 1931. Scale for indicating the amount of unused film remaining on the 
reels of a motion picture camera. A scale is provided which contacts with the 
film reel and shifts in accordance with the delivery of the film from the reel to 
render visible calibrations on the scale which indicate the amount of unused film 
still on the reel. 

1,812,212. Fire Shutter for Motion Picture Projector. W. H. MEYER. 
June 30, 1931. A fire shutter for motion picture projectors in which the shutter 
is perforated over its entire area. The perforations in the center of the fire shutter 
are smaller than the surrounding perforations and graduate in size as they extend 
outward from the center of the fire shutter. This form of fire shutter is par- 
ticularly adapted for home type motion picture machines. The shutter is auto- 
matically positioned in the path of light rays between the lamp and the film when 
the projector is stopped and positioned away from the path of light rays when 
the projector is operated and the film is in motion. 

1,812,303. Elongated Light-Sensitive Element for Reproducing Sound. 
F. H. OWENS. Assigned to Owens Development Corporation. June 30, 1931. 
An elongated light-sensitive element is used for translating modulated light rays 
into electrical impulses. The light rays are spread during their passage to the 
light-sensitive element so that the light rays will enter 'the element over sub- 
stantially its entire length, thus producing a maximum volume of reproduced 
sound. An elongated housing is provided for the light-sensitive element which 
provides for the reflection of light rays to secure maximum illumination of the 
light-sensitive element. 

1,812,402. Electrooptical Transmission System. F. GRAY. Assigned to 
Bell Telephone Laboratories, Inc. June 30, 1931. An apparatus for producing 
television images, comprising a spirally arranged row of primary sources of 
light, such as electric lamps, attached to a revolving disk near the periphery 
thereof, and adapted to cross the field of view in succession to build up an image. 
Each lamp is connected to a circuit including a winding attached to the disk 
through which the lamp is inductively energized, while passing across the field of 
view, by a source of image current having variations corresponding to the tone 
values of successively scanned elemental areas of a field of view. The image 
current may be a current of varying amplitude which is supplied directly to the 
lamps through an inductive coupling. 

1,812,405. Multiple Channel Electrooptical Transmission System. H. E. 
IVES. Assigned to Bell Telephone Laboratories, Inc. June 30, 1931. This 
invention provides for splitting the total scanning frequency band of the photo- 
electric signal current into a number of narrower frequency bands or sections by 
means of filters or the like, so that the different sections may be segregated for 
any purpose, such as transmission over different circuits. The low energy gaps 
between the groups of frequency components permit the composite current re- 

Sept., 1931] PATENT ABSTRACTS 467 

suiting from scanning to be so divided without interfering with essential fre- 
quencies. When the narrow or sub-groups are transmitted over separate channels 
or circuits, respectively, each circuit may have transmission characteristics suit- 
able for the transmission of one of the sections of the photoelectric current, the 
splitting being made in the above-mentioned gaps; or each segregated section or 
band of frequencies so split may be transposed by combination, respectively, 
with suitable currents of different constant frequencies, to the same or different 
part of the frequency spectrum for transmission over different circuits having 
similar or suitable characteristics, thus permitting the use of comparatively low- 
grade circuits or circuits having a comparatively limited frequency range. The 
different sections, after being transmitted, may be restored to their original fre- 
quency position; thereby producing a signal current corresponding to the original 
photoelectric current. 

1,812,763. Photoelectric Cell Bridge for Measuring Light Intensity. W. E. 
STORY, JR. Assigned to General Electric Company. June 30, 1931. The in- 
tensity of light from two sources may be compared by placing a photoelectric 
device in each of two arms of a Wheatstone bridge ; and the illumination from any 
lamp may be compared with that from a standard lamp in such a way as to avoid 
the visual comparison of illumination. The photoelectric cells which are exposed 
to the sources of light are employed to accurately change the resistance of the 
Wheatstone bridge circuit for operating a calibrated indicator. 

(Abstracts compiled by John B. Brady, Patent Attorney, Washington, D. C.) 


Seeing A Partnership of Lighting and Vision. M. LUCKIESH, Director, 
Lighting Research Laboratory, General Electric Co., Nela Park, Cleveland, 
AND FRANK K. Moss, also of the Lighting Research Laboratory, Nela Park. 
Williams & Wilkins Co., Baltimore, Md. 241 pp. 63 illustrations; also an 
illustrated supplement, "A Demonstration Visual Test." $5.00. This book 
represents an attempt to strike a new note in the science of lighting and as such, 
goes beyond the usual work on illuminating engineering. While much data of 
the usual variety have necessarily been included, the aim is primarily to inter- 
pret their influence in determining the ability to see well. Consequently, such 
important factors as visual acuity, contrast, brightness adaptation, and glare 
are discussed in considerable detail in relation to the speed and accuracy of 
vision. There has been included much laboratory information along this line 
that is not available in the previous works on lighting, and which adds consider- 
ably to the value of the book. 

Two very useful chapters deal with brightness and the speed of seeing. The 
former explains in a simple manner how brightness influences visual acuity 
in relation to threshold values and contrast, and the two chapters together cover 
the relation between these factors and the speed with which one can distinguish 
test objects. Another important chapter deals with the speed of adaptation 
and the necessity for proper transition lighting in passing from brilliantly illumi- 
nated places to darker ones, as from outsides to interiors. Other subjects cov- 
ered in some detail are glare and visibility, spectral character of light, and the 
nature and prevalence of subnormal vision. Enough data on the present stand- 
ard practice in illuminating engineering have been included in the book to make 
it a comprehensive survey of the subject, and to make it useful to anyone con- 
cerned with practical applications. At the end there are a number of charts 
illustrating the relationships discussed previously. In the supplement there are 
over twenty charts and figures which, together with an explanation, comprise 
a visual test to be used as a practical demonstration of the value of better lighting. 
The book as a whole should prove valuable to anyone who is at all interested in 
the subject of "Seeing." 





J. I. CRABTREE, Eastman Kodak Co., Rochester, N. Y. 

L. C. PORTER, General Electric Co., Nela Park, Cleveland. Ohio 


K. C. D. HICKMAN, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 

J. H. KURLANDER, Westhighouse Lamp Co., Bloomfield, N. J. 

H. T. COWLING, Eastman Teaching Films, Inc., Rochester, N. Y. 

Board of Governors 

F. C. BADGLEY, Canadian Government Motion Picture Bureau, Ottawa, Canada 
H. T. COWLING, Eastman Teaching Films, Inc., 343 State St., Rochester, N. Y. 
J. I. CRABTREE, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
K. C. D. HICKMAN, Research Laboratories, Eastman Kodak Co., Rochester, N. Y. 
W. C. HUBBARD, General Electric Vapor Lamp Co., Hoboken, N. J. 
J. E. JENKINS, Jenkins & Adair, Inc., 3333 Belmont Avenue, Chicago, 111. 
J. H. KURLANDER, Westinghouse Lamp Co., Bloomfield, N. J. 
W. C. KUNZMANN, National Carbon Co., Cleveland, Ohio 

D. MACKENZIE, Electrical Research Products, Inc., 7046 Hollywood Blvd., 

Los Angeles, Calif. 
M. W. PALMER, Paramount Publix Corp., 35-11 35th Ave., Long Island City, 

N. Y. 
L. C. PORTER, General Electric Co., Nela Park, Cleveland, Ohio 

E. I. SPONABLE, 277 Park Ave., New York, N. Y. 



[J. S. M. P. E. 










W. V. D. KELLEY, Chairman 




W. C. KUNZMANN, Chairman 

C. L. GREGORY, Chairman 




Membership and Subscription 
H. T. COWLING, Chairman 












O. M. GLUNT, Chairman 


D. McNicoL 


G. E. MATTHEWS, Chairman 












Sept., 1931] 




Projection Practice 
H. RUBIN, Chairman 



P. A. McGuiRE 




Projection Screens 
S. K. WOLF, Chairman 






Projection Theory 
W. B. RAYTON, Chairman 





W. WHITMORE, Chairman 




H. B. SANTEE, Chairman 




Standards and Nomenclature 
A. C. HARDY, Chairman 




Studio Lighting 
M. W. PALMER, Chairman 


Chicago Section 

J. E. JENKINS, Chairman R. P. BURNS, Manager 

R. F. MITCHELL, Sec.-Treas. O. B. DEPUE, Manager 

New York Section 
M. W. PALMER, Chairman M. C. BATSEL, Manager 

D. E. HYNDMAN, Sec.-Treas. T. E. SHEA, Manager 

Pacific Coast Section 

D. MACKENZIE, Chairman G. MITCHELL, Manager 

E. HUSE, Secretary H. C. SILENT, Manager 

L. E. CLARK, Treasurer 


Baker, F. F.: Born April 10, 1890, at Hamburg, Iowa. Tabor College. Mo- 
tion picture cameraman since 1911 ; specialist in trick and miniature photograpy, 
1921-29; Technicolor Motion Picture Corp., 1929-31. 

Ceccarini, O. O.: Born March 21, 1894, at Montefiascone, Italy. Physics 
and mathematics, Technical Institute, Rome, Italy; post-graduate work, Union 
College. Testing and general engineering departments, General Electric Co., 
1915-19; research engineer, Bell Telephone Laboratories, 1920-27; assistant 
chief engineer, Vitaphone Corp., 1927-28; development engineering, Metro-Gold- 
wyn-Mayer Studios, 1928 to date. 

Falge, F. M.: Graduate U. S. Naval Academy, 1924; sales department, West- 
inghouse Electric & Mfg. Co. 1924-26; engineer, National Lamp Works 
Nela Park, 1926-28; lighting specialist, production and research departments, 
Paramount Publix Corp., 1928-30; instructor, Paramount Theatre Managers 
Training School, 1930; engineer, Beaded Screen Corp., 1931. 

Felstead, C.: Born December 21, 1902, at Buffalo, N. Y. University of 
Southern California, 1924-28; in charge of construction and operation of limited 
commercial radio stations, Thos. H. Ince Studio, 1923-24; research laboratory, 
Gilfillan Radio Corp., 1928; supervising construction and installation of radio 
stations, Universal Pictures Corp., 1928; sound engineer, Universal Pictures 
Corp., 1928 to date. 

Hoke, I. B.: Born May 26, 1894, at Rock Island, 111. Motion picture photog- 
rapher, 1927; photographer, Signal Corps, U, S. Army, 1927-19; free lance mo- 
tion picture photographer, 1919 to date. 

Kuhn, J. J.: Born 1891, at Elizabeth, N. J. Power transmitting machinery 
department, A. &. F. Brown Co., 1909-19; engineering department, Western 
Electric Co., 1919-25; in charge of mechanical design of Public